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rfc:std:std92

[Note that this file is a concatenation of more than one RFC.]

Internet Engineering Task Force (IETF) M. Sweet Request for Comments: 8010 Apple Inc. Obsoletes: 2910, 3382 I. McDonald Category: Standards Track High North, Inc. ISSN: 2070-1721 January 2017

       Internet Printing Protocol/1.1: Encoding and Transport

Abstract

 The Internet Printing Protocol (IPP) is an application-level protocol
 for distributed printing using Internet tools and technologies.  This
 document defines the rules for encoding IPP operations, attributes,
 and values into the Internet MIME media type called
 "application/ipp".  It also defines the rules for transporting a
 message body whose Content-Type is "application/ipp" over HTTP and/or
 HTTPS.  The IPP data model and operation semantics are described in
 "Internet Printing Protocol/1.1: Model and Semantics" (RFC 8011).
 This document obsoletes RFCs 2910 and 3382.

Status of This Memo

 This is an Internet Standards Track document.
 This document is a product of the Internet Engineering Task Force
 (IETF).  It represents the consensus of the IETF community.  It has
 received public review and has been approved for publication by the
 Internet Engineering Steering Group (IESG).  Further information on
 Internet Standards is available in Section 2 of RFC 7841.
 Information about the current status of this document, any errata,
 and how to provide feedback on it may be obtained at
 http://www.rfc-editor.org/info/rfc8010.

Sweet & McDonald Standards Track [Page 1] RFC 8010 IPP/1.1: Encoding and Transport January 2017

Copyright Notice

 Copyright (c) 2017 IETF Trust and the persons identified as the
 document authors.  All rights reserved.
 This document is subject to BCP 78 and the IETF Trust's Legal
 Provisions Relating to IETF Documents
 (http://trustee.ietf.org/license-info) in effect on the date of
 publication of this document.  Please review these documents
 carefully, as they describe your rights and restrictions with respect
 to this document.  Code Components extracted from this document must
 include Simplified BSD License text as described in Section 4.e of
 the Trust Legal Provisions and are provided without warranty as
 described in the Simplified BSD License.

Table of Contents

 1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   4
 2.  Conventions Used in This Document . . . . . . . . . . . . . .   5
   2.1.  Requirements Language . . . . . . . . . . . . . . . . . .   5
   2.2.  Printing Terminology  . . . . . . . . . . . . . . . . . .   5
   2.3.  Abbreviations . . . . . . . . . . . . . . . . . . . . . .   6
 3.  Encoding of the Operation Layer . . . . . . . . . . . . . . .   6
   3.1.  Picture of the Encoding . . . . . . . . . . . . . . . . .   8
     3.1.1.  Request and Response  . . . . . . . . . . . . . . . .   8
     3.1.2.  Attribute Group . . . . . . . . . . . . . . . . . . .   9
     3.1.3.  Attribute . . . . . . . . . . . . . . . . . . . . . .   9
     3.1.4.  Attribute-with-one-value  . . . . . . . . . . . . . .  10
     3.1.5.  Additional-value  . . . . . . . . . . . . . . . . . .  11
     3.1.6.  Collection Attribute  . . . . . . . . . . . . . . . .  12
     3.1.7.  Member Attributes . . . . . . . . . . . . . . . . . .  13
     3.1.8.  Alternative Picture of the Encoding of a Request or a
             Response  . . . . . . . . . . . . . . . . . . . . . .  14
   3.2.  Syntax of Encoding  . . . . . . . . . . . . . . . . . . .  15
   3.3.  Attribute-group . . . . . . . . . . . . . . . . . . . . .  16
   3.4.  Required Parameters . . . . . . . . . . . . . . . . . . .  18
     3.4.1.  "version-number"  . . . . . . . . . . . . . . . . . .  18
     3.4.2.  "operation-id"  . . . . . . . . . . . . . . . . . . .  18
     3.4.3.  "status-code" . . . . . . . . . . . . . . . . . . . .  19
     3.4.4.  "request-id"  . . . . . . . . . . . . . . . . . . . .  19
   3.5.  Tags  . . . . . . . . . . . . . . . . . . . . . . . . . .  19
     3.5.1.  "delimiter-tag" Values  . . . . . . . . . . . . . . .  19
     3.5.2.  "value-tag" Values  . . . . . . . . . . . . . . . . .  20
   3.6.  "name-length" . . . . . . . . . . . . . . . . . . . . . .  23
   3.7.  (Attribute) "name"  . . . . . . . . . . . . . . . . . . .  23
   3.8.  "value-length"  . . . . . . . . . . . . . . . . . . . . .  23
   3.9.  (Attribute) "value" . . . . . . . . . . . . . . . . . . .  24
   3.10. Data  . . . . . . . . . . . . . . . . . . . . . . . . . .  25

Sweet & McDonald Standards Track [Page 2] RFC 8010 IPP/1.1: Encoding and Transport January 2017

 4.  Encoding of Transport Layer . . . . . . . . . . . . . . . . .  26
   4.1.  Printer URI, Job URI, and Job ID  . . . . . . . . . . . .  26
 5.  IPP URI Schemes . . . . . . . . . . . . . . . . . . . . . . .  28
 6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  29
 7.  Internationalization Considerations . . . . . . . . . . . . .  31
 8.  Security Considerations . . . . . . . . . . . . . . . . . . .  31
   8.1.  Security Conformance Requirements . . . . . . . . . . . .  31
     8.1.1.  Digest Authentication . . . . . . . . . . . . . . . .  32
     8.1.2.  Transport Layer Security (TLS)  . . . . . . . . . . .  32
   8.2.  Using IPP with TLS  . . . . . . . . . . . . . . . . . . .  33
 9.  Interoperability with Other IPP Versions  . . . . . . . . . .  33
   9.1.  The "version-number" Parameter  . . . . . . . . . . . . .  34
   9.2.  Security and URI Schemes  . . . . . . . . . . . . . . . .  34
 10. Changes since RFC 2910  . . . . . . . . . . . . . . . . . . .  35
 11. References  . . . . . . . . . . . . . . . . . . . . . . . . .  36
   11.1.  Normative References . . . . . . . . . . . . . . . . . .  36
   11.2.  Informative References . . . . . . . . . . . . . . . . .  38
 Appendix A.  Protocol Examples  . . . . . . . . . . . . . . . . .  40
   A.1.  Print-Job Request . . . . . . . . . . . . . . . . . . . .  40
   A.2.  Print-Job Response (Successful) . . . . . . . . . . . . .  41
   A.3.  Print-Job Response (Failure)  . . . . . . . . . . . . . .  42
   A.4.  Print-Job Response (Success with Attributes Ignored)  . .  43
   A.5.  Print-URI Request . . . . . . . . . . . . . . . . . . . .  45
   A.6.  Create-Job Request  . . . . . . . . . . . . . . . . . . .  46
   A.7.  Create-Job Request with Collection Attributes . . . . . .  46
   A.8.  Get-Jobs Request  . . . . . . . . . . . . . . . . . . . .  48
   A.9.  Get-Jobs Response . . . . . . . . . . . . . . . . . . . .  49
 Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .  51
 Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  51

Sweet & McDonald Standards Track [Page 3] RFC 8010 IPP/1.1: Encoding and Transport January 2017

1. Introduction

 This document contains the rules for encoding IPP operations and
 describes two layers: the transport layer and the operation layer.
 The transport layer consists of an HTTP request and response.  All
 IPP implementations support HTTP/1.1, the relevant parts of which are
 described in the following RFCs:
 o  Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing
    [RFC7230]
 o  Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content
    [RFC7231]
 o  Hypertext Transfer Protocol (HTTP/1.1): Conditional Requests
    [RFC7232]
 o  Hypertext Transfer Protocol (HTTP/1.1): Caching [RFC7234]
 o  Hypertext Transfer Protocol (HTTP/1.1): Authentication [RFC7235]
 o  The 'Basic' HTTP Authentication Scheme [RFC7617]
 o  HTTP Digest Access Authentication [RFC7616]
 IPP implementations can support HTTP/2, which is described in the
 following RFCs:
 o  Hypertext Transfer Protocol Version 2 (HTTP/2) [RFC7540]
 o  HPACK - Header Compression for HTTP/2 [RFC7541]
 This document specifies the HTTP headers that an IPP implementation
 supports.
 The operation layer consists of a message body in an HTTP request or
 response.  The "Internet Printing Protocol/1.1: Model and Semantics"
 document [RFC8011] and subsequent extensions (collectively known as
 the IPP Model) define the semantics of such a message body and the
 supported values.  This document specifies the encoding of an IPP
 request and response message.

Sweet & McDonald Standards Track [Page 4] RFC 8010 IPP/1.1: Encoding and Transport January 2017

2. Conventions Used in This Document

2.1. Requirements Language

 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
 document are to be interpreted as described in [RFC2119].

2.2. Printing Terminology

 Client: Initiator of outgoing IPP session requests and sender of
 outgoing IPP operation requests (Hypertext Transfer Protocol --
 HTTP/1.1 [RFC7230] User Agent).
 Document: An object created and managed by a Printer that contains
 description, processing, and status information.  A Document object
 may have attached data and is bound to a single Job.
 'ipp' URI: An IPP URI as defined in [RFC3510].
 'ipps' URI: An IPPS URI as defined in [RFC7472].
 Job: An object created and managed by a Printer that contains
 description, processing, and status information.  The Job also
 contains zero or more Document objects.
 Logical Device: A print server, software service, or gateway that
 processes Jobs and either forwards or stores the processed Job or
 uses one or more Physical Devices to render output.
 Model: The semantics of operations, attributes, values, and status-
 codes used in the Internet Printing Protocol as defined in the
 Internet Printing Protocol/1.1: Model and Semantics document
 [RFC8011] and subsequent extensions.
 Output Device: A single Logical or Physical Device.
 Physical Device: A hardware implementation of an endpoint device,
 e.g., a marking engine, a fax modem, etc.
 Printer: Listener for incoming IPP session requests and receiver of
 incoming IPP operation requests (Hypertext Transfer Protocol --
 HTTP/1.1 [RFC7230] Server) that represents one or more Physical
 Devices or a Logical Device.

Sweet & McDonald Standards Track [Page 5] RFC 8010 IPP/1.1: Encoding and Transport January 2017

2.3. Abbreviations

 ABNF: Augmented Backus-Naur Form [RFC5234]
 ASCII: American Standard Code for Information Interchange [RFC20]
 HTTP: Hypertext Transfer Protocol [RFC7230]
 HTTPS: HTTP over TLS [RFC2818]
 IANA: Internet Assigned Numbers Authority
 IEEE: Institute of Electrical and Electronics Engineers
 IESG: Internet Engineering Steering Group
 IPP: Internet Printing Protocol (this document and [PWG5100.12])
 ISTO: IEEE Industry Standards and Technology Organization
 LPD: Line Printer Daemon Protocol [RFC1179]
 PWG: IEEE-ISTO Printer Working Group
 RFC: Request for Comments
 TCP: Transmission Control Protocol [RFC793]
 TLS: Transport Layer Security [RFC5246]
 URI: Uniform Resource Identifier [RFC3986]
 URL: Uniform Resource Locator [RFC3986]
 UTF-8: Unicode Transformation Format - 8-bit [RFC3629]

3. Encoding of the Operation Layer

 The operation layer is the message body part of the HTTP request or
 response and it MUST contain a single IPP operation request or IPP
 operation response.  Each request or response consists of a sequence
 of values and attribute groups.  Attribute groups consist of a
 sequence of attributes each of which is a name and value.  Names and
 values are ultimately sequences of octets.
 The encoding consists of octets as the most primitive type.  There
 are several types built from octets, but three important types are
 integers, character strings, and octet strings, on which most other

Sweet & McDonald Standards Track [Page 6] RFC 8010 IPP/1.1: Encoding and Transport January 2017

 data types are built.  Every character string in this encoding MUST
 be a sequence of characters where the characters are associated with
 some charset [RFC2978] and some natural language.  A character string
 MUST be in "reading order" with the first character in the value
 (according to reading order) being the first character in the
 encoding.  A character string whose associated charset is US-ASCII
 and whose associated natural language is US English is henceforth
 called a US-ASCII-STRING.  A character string whose associated
 charset and natural language are specified in a request or response
 as described in the Model is henceforth called a LOCALIZED-STRING.
 An octet string MUST be in "Model order" with the first octet in the
 value (according to the Model order) being the first octet in the
 encoding.  Every integer in this encoding MUST be encoded as a signed
 integer using two's-complement binary encoding with big-endian format
 (also known as "network order" and "most significant byte first").
 The number of octets for an integer MUST be 1, 2, or 4, depending on
 usage in the protocol.  A one-octet integer, henceforth called a
 SIGNED-BYTE, is used for the version-number and tag fields.  A two-
 byte integer, henceforth called a SIGNED-SHORT, is used for the
 operation-id, status-code, and length fields.  A four-byte integer,
 henceforth called a SIGNED-INTEGER, is used for value fields and the
 request-id.
 The following two sections present the encoding of the operation
 layer in two ways:
 o  informally through pictures and description
 o  formally through Augmented Backus-Naur Form (ABNF), as specified
    by RFC 5234 [RFC5234]
 An operation request or response MUST use the encoding described in
 these two sections.

Sweet & McDonald Standards Track [Page 7] RFC 8010 IPP/1.1: Encoding and Transport January 2017

3.1. Picture of the Encoding

3.1.1. Request and Response

 An operation request or response is encoded as follows:
  1. ———————————————-

| version-number | 2 bytes - required

  1. ———————————————-

| operation-id (request) |

 |                      or                     |   2 bytes  - required
 |               status-code (response)        |
 -----------------------------------------------
 |                   request-id                |   4 bytes  - required
 -----------------------------------------------
 |                 attribute-group             |   n bytes - 0 or more
 -----------------------------------------------
 |              end-of-attributes-tag          |   1 byte   - required
 -----------------------------------------------
 |                     data                    |   q bytes  - optional
 -----------------------------------------------
                     Figure 1: IPP Message Format
 The first three fields in the above diagram contain the value of
 attributes described in Section 4.1.1 of the Model and Semantics
 document [RFC8011].
 The fourth field is the "attribute-group" field, and it occurs 0 or
 more times.  Each "attribute-group" field represents a single group
 of attributes, such as an Operation Attributes group or a Job
 Attributes group (see the Model).  The Model specifies the required
 attribute groups and their order for each operation request and
 response.
 The "end-of-attributes-tag" field is always present, even when the
 "data" is not present.  The Model specifies whether the "data" field
 is present for each operation request and response.

Sweet & McDonald Standards Track [Page 8] RFC 8010 IPP/1.1: Encoding and Transport January 2017

3.1.2. Attribute Group

 Each "attribute-group" field is encoded as follows:
  1. ———————————————-

| begin-attribute-group-tag | 1 byte

  1. ———————————————————

| attribute | p bytes |- 0 or more

  1. ———————————————————
                  Figure 2: Attribute Group Encoding
 An "attribute-group" field contains zero or more "attribute" fields.
 Note that the values of the "begin-attribute-group-tag" field and the
 "end-of-attributes-tag" field are called "delimiter-tags".

3.1.3. Attribute

 An "attribute" field is encoded as follows:
  1. ———————————————-

| attribute-with-one-value | q bytes

  1. ———————————————————

| additional-value | r bytes |- 0 or more

  1. ———————————————————
                     Figure 3: Attribute Encoding
 When an attribute is single valued (e.g., "copies" with a value of
 10) or multi-valued with one value (e.g., "sides-supported" with just
 the value 'one-sided'), it is encoded with just an "attribute-with-
 one-value" field.  When an attribute is multi-valued with n values
 (e.g., "sides-supported" with the values 'one-sided' and 'two-sided-
 long-edge'), it is encoded with an "attribute-with-one-value" field
 followed by n-1 "additional-value" fields.

Sweet & McDonald Standards Track [Page 9] RFC 8010 IPP/1.1: Encoding and Transport January 2017

3.1.4. Attribute-with-one-value

 Each "attribute-with-one-value" field is encoded as follows:
  1. ———————————————-

| value-tag | 1 byte

  1. ———————————————-

| name-length (value is u) | 2 bytes

  1. ———————————————-

| name | u bytes

  1. ———————————————-

| value-length (value is v) | 2 bytes

  1. ———————————————-

| value | v bytes

  1. ———————————————-
               Figure 4: Single Value Attribute Encoding
 An "attribute-with-one-value" field is encoded with five subfields:
 o  The "value-tag" field specifies the attribute syntax, e.g., 0x44
    for the attribute syntax 'keyword'.
 o  The "name-length" field specifies the length of the "name" field
    in bytes, e.g., u in the above diagram or 15 for the name "sides-
    supported".
 o  The "name" field contains the textual name of the attribute, e.g.,
    "sides-supported".
 o  The "value-length" field specifies the length of the "value" field
    in bytes, e.g., v in the above diagram or 9 for the (keyword)
    value 'one-sided'.
 o  The "value" field contains the value of the attribute, e.g., the
    textual value 'one-sided'.

Sweet & McDonald Standards Track [Page 10] RFC 8010 IPP/1.1: Encoding and Transport January 2017

3.1.5. Additional-value

 Each "additional-value" field is encoded as follows:
  1. ———————————————-

| value-tag | 1 byte

  1. ———————————————-

| name-length (value is 0x0000) | 2 bytes

  1. ———————————————-

| value-length (value is w) | 2 bytes

  1. ———————————————-

| value | w bytes

  1. ———————————————-
             Figure 5: Additional Attribute Value Encoding
 An "additional-value" is encoded with four subfields:
 o  The "value-tag" field specifies the attribute syntax, e.g., 0x44
    for the attribute syntax 'keyword'.
 o  The "name-length" field has the value of 0 in order to signify
    that it is an "additional-value".  The value of the "name-length"
    field distinguishes an "additional-value" field ("name-length" is
    0) from an "attribute-with-one-value" field ("name-length" is not
    0).
 o  The "value-length" field specifies the length of the "value" field
    in bytes, e.g., w in the above diagram or 19 for the (keyword)
    value 'two-sided-long-edge'.
 o  The "value" field contains the value of the attribute, e.g., the
    textual value 'two-sided-long-edge'.

Sweet & McDonald Standards Track [Page 11] RFC 8010 IPP/1.1: Encoding and Transport January 2017

3.1.6. Collection Attribute

 Collection attributes create a named group containing related
 "member" attributes.  The "attribute-with-one-value" field for a
 collection attribute is encoded as follows:
  1. ———————————————-

| value-tag (value is 0x34) | 1 byte

  1. ———————————————-

| name-length (value is u) | 2 bytes

  1. ———————————————-

| name | u bytes

  1. ———————————————-

| value-length (value is 0x0000) | 2 bytes

  1. ———————————————————-

| member-attribute | q bytes |-0 or more

  1. ———————————————————-

| end-value-tag (value is 0x37) | 1 byte

  1. ———————————————-

| end-name-length (value is 0x0000) | 2 bytes

  1. ———————————————-

| end-value-length (value is 0x0000) | 2 bytes

  1. ———————————————-
                Figure 6: Collection Attribute Encoding
 Collection attribute is encoded with eight subfields:
 o  The "value-tag" field specifies the start attribute syntax: 0x34
    for the attribute syntax 'begCollection'.
 o  The "name-length" field specifies the length of the "name" field
    in bytes, e.g., u in the above diagram or 9 for the name "media-
    col".  Additional collection attribute values use a name length of
    0x0000.
 o  The "name" field contains the textual name of the attribute, e.g.,
    "media-col".
 o  The "value-length" field specifies a length of 0x0000.
 o  The "member-attribute" field contains member attributes encoded as
    defined in Section 3.1.7.
 o  The "end-value-tag" field specifies the end attribute syntax: 0x37
    for the attribute syntax 'endCollection'.
 o  The "end-name-length" field specifies a length of 0x0000.

Sweet & McDonald Standards Track [Page 12] RFC 8010 IPP/1.1: Encoding and Transport January 2017

 o  The "end-value-length" field specifies a length of 0x0000.

3.1.7. Member Attributes

 Each "member-attribute" field is encoded as follows:
  1. ———————————————-

| value-tag (value is 0x4a) | 1 byte

  1. ———————————————-

| name-length (value is 0x0000) | 2 bytes

  1. ———————————————-

| value-length (value is w) | 2 bytes

  1. ———————————————-

| value (member-name) | w bytes

  1. ———————————————-

| member-value-tag | 1 byte

  1. ———————————————-

| name-length (value is 0x0000) | 2 bytes

  1. ———————————————-

| member-value-length (value is x) | 2 bytes

  1. ———————————————-

| member-value | x bytes

  1. ———————————————-
                  Figure 7: Member Attribute Encoding
 A "member-attribute" is encoded with eight subfields:
 o  The "value-tag" field specifies 0x4a for the attribute syntax
    'memberAttrName'.
 o  The "name-length" field has the value of 0 in order to signify
    that it is a "member-attribute" contained in the collection.
 o  The "value-length" field specifies the length of the "value" field
    in bytes, e.g., w in the above diagram or 10 for the member
    attribute name 'media-type'.  Additional member attribute values
    are specified using a value length of 0.
 o  The "value" field contains the name of the member attribute, e.g.,
    the textual value 'media-type'.
 o  The "member-value-tag" field specifies the attribute syntax for
    the member attribute, e.g., 0x44 for the attribute syntax
    'keyword'.

Sweet & McDonald Standards Track [Page 13] RFC 8010 IPP/1.1: Encoding and Transport January 2017

 o  The second "name-length" field has the value of 0 in order to
    signify that it is a "member-attribute" contained in the
    collection.
 o  The "member-value-length" field specifies the length of the member
    attribute value, e.g., x in the above diagram or 10 for the value
    'stationery'.
 o  The "member-value" field contains the value of the attribute,
    e.g., the textual value 'stationery'.

3.1.8. Alternative Picture of the Encoding of a Request or a Response

 From the standpoint of a parser that performs an action based on a
 "tag" value, the encoding consists of:
  1. ———————————————-

| version-number | 2 bytes - required

  1. ———————————————-

| operation-id (request) |

 |                      or                     |   2 bytes  - required
 |               status-code (response)        |
 -----------------------------------------------
 |                   request-id                |   4 bytes  - required
 -----------------------------------------------------------
 |        tag (delimiter-tag or value-tag)     |   1 byte  |
 -----------------------------------------------           |-0 or more
 |           empty or rest of attribute        |   x bytes |
 -----------------------------------------------------------
 |              end-of-attributes-tag          |   1 byte   - required
 -----------------------------------------------
 |                     data                    |   y bytes  - optional
 -----------------------------------------------
                Figure 8: Encoding Based on Value Tags
 The following shows what fields the parser would expect after each
 type of "tag":
 o  "begin-attribute-group-tag": expect zero or more "attribute"
    fields
 o  "value-tag": expect the remainder of an "attribute-with-one-value"
    or an "additional-value"
 o  "end-of-attributes-tag": expect that "attribute" fields are
    complete and there is optional "data"

Sweet & McDonald Standards Track [Page 14] RFC 8010 IPP/1.1: Encoding and Transport January 2017

3.2. Syntax of Encoding

 The ABNF [RFC5234] syntax for an IPP message is shown in Figure 9.
 ipp-message  = ipp-request / ipp-response
 ipp-request  = version-number operation-id request-id
                *attribute-group end-of-attributes-tag data
 ipp-response = version-number status-code request-id
                *attribute-group end-of-attributes-tag  data
 version-number       = major-version-number minor-version-number
 major-version-number = SIGNED-BYTE
 minor-version-number = SIGNED-BYTE
 operation-id = SIGNED-SHORT     ; mapping from model
 status-code  = SIGNED-SHORT     ; mapping from model
 request-id   = SIGNED-INTEGER   ; whose value is > 0
 attribute-group          = begin-attribute-group-tag *attribute
 attribute                = attribute-with-one-value *additional-value
 attribute-with-one-value = value-tag name-length name
                            value-length value
 additional-value         = value-tag zero-name-length
                            value-length value
 name-length  = SIGNED-SHORT     ; number of octets of 'name'
 name         = LALPHA *( LALPHA / DIGIT / "-" / "_" / "." )
 value-length = SIGNED-SHORT     ; number of octets of 'value'
 value        = OCTET-STRING
 data         = OCTET-STRING
 zero-name-length          = %x00.00           ; name-length of 0
 value-tag                 = %x10-ff           ; see Section 3.5.2
 begin-attribute-group-tag = %x00-02 / %x04-0f ; see Section 3.5.1
 end-of-attributes-tag     = %x03              ; tag of 3
                                               ; see Section 3.5.1
 SIGNED-BYTE    = BYTE
 SIGNED-SHORT   = 2BYTE
 SIGNED-INTEGER = 4BYTE
 DIGIT          = %x30-39        ; "0" to "9"
 LALPHA         = %x61-7A        ; "a" to "z"
 BYTE           = %x00-ff
 OCTET-STRING   = *BYTE
                 Figure 9: ABNF of IPP Message Format

Sweet & McDonald Standards Track [Page 15] RFC 8010 IPP/1.1: Encoding and Transport January 2017

 Figure 10 defines additional terms that are referenced in this
 document and provides an alternate grouping of the delimiter tags.
 delimiter-tag = begin-attribute-group-tag /   ; see Section 3.5.1
           end-of-attributes-tag
 begin-attribute-group-tag = %x00 / operation-attributes-tag /
    job-attributes-tag / printer-attributes-tag /
    unsupported-attributes-tag / future-group-tags
 operation-attributes-tag   = %x01             ; tag of 1
 job-attributes-tag         = %x02             ; tag of 2
 end-of-attributes-tag      = %x03             ; tag of 3
 printer-attributes-tag     = %x04             ; tag of 4
 unsupported-attributes-tag = %x05             ; tag of 5
 future-group-tags          = %x06-0f          ; future extensions
               Figure 10: ABNF for Attribute Group Tags

3.3. Attribute-group

 Each "attribute-group" field MUST be encoded with the "begin-
 attribute-group-tag" field followed by zero or more "attribute" sub-
 fields.

Sweet & McDonald Standards Track [Page 16] RFC 8010 IPP/1.1: Encoding and Transport January 2017

 Table 1 maps the Model group name to value of the "begin-attribute-
 group-tag" field:
 +----------------+--------------------------------------------------+
 | Model Document | "begin-attribute-group-tag" field values         |
 | Group          |                                                  |
 +----------------+--------------------------------------------------+
 | Operation      | "operations-attributes-tag"                      |
 | Attributes     |                                                  |
 +----------------+--------------------------------------------------+
 | Job Template   | "job-attributes-tag"                             |
 | Attributes     |                                                  |
 +----------------+--------------------------------------------------+
 | Job Object     | "job-attributes-tag"                             |
 | Attributes     |                                                  |
 +----------------+--------------------------------------------------+
 | Unsupported    | "unsupported-attributes-tag"                     |
 | Attributes     |                                                  |
 +----------------+--------------------------------------------------+
 | Requested      | (Get-Job-Attributes) "job-attributes-tag"        |
 | Attributes     |                                                  |
 +----------------+--------------------------------------------------+
 | Requested      | (Get-Printer-Attributes)"printer-attributes-tag" |
 | Attributes     |                                                  |
 +----------------+--------------------------------------------------+
 | Document       | in a special position at the end of the message  |
 | Content        | as described in Section 3.1.1.                   |
 +----------------+--------------------------------------------------+
                         Table 1: Group Values
 For each operation request and response, the Model prescribes the
 required and optional attribute groups, along with their order.
 Within each attribute group, the Model prescribes the required and
 optional attributes, along with their order.
 When the Model requires an attribute group in a request or response
 and the attribute group contains zero attributes, a request or
 response SHOULD encode the attribute group with the "begin-attribute-
 group-tag" field followed by zero "attribute" fields.  For example,
 if the Client requests a single unsupported attribute with the Get-
 Printer-Attributes operation, the Printer MUST return no "attribute"
 fields, and it SHOULD return a "begin-attribute-group-tag" field for
 the Printer Attributes group.  The Unsupported Attributes group is
 not such an example.  According to the Model, the Unsupported
 Attributes group SHOULD be present only if the Unsupported Attributes
 group contains at least one attribute.

Sweet & McDonald Standards Track [Page 17] RFC 8010 IPP/1.1: Encoding and Transport January 2017

 A receiver of a request MUST be able to process the following as
 equivalent empty attribute groups:
 a.  A "begin-attribute-group-tag" field with zero following
     "attribute" fields.
 b.  A missing, but expected, "begin-attribute-group-tag" field.
 When the Model requires a sequence of an unknown number of attribute
 groups, each of the same type, the encoding MUST contain one "begin-
 attribute-group-tag" field for each attribute group, even when an
 "attribute-group" field contains zero "attribute" sub-fields.  For
 example, the Get-Jobs operation may return zero attributes for some
 Jobs and not others.  The "begin-attribute-group-tag" field followed
 by zero "attribute" fields tells the recipient that there is a Job in
 queue for which no information is available except that it is in the
 queue.

3.4. Required Parameters

 Some operation elements are called parameters in the Model.  They
 MUST be encoded in a special position and they MUST NOT appear as
 operation attributes.  These parameters are described in the
 subsections below.

3.4.1. "version-number"

 The "version-number" field consists of a major and minor version-
 number, each of which is represented by a SIGNED-BYTE.  The major
 version-number is the first byte of the encoding and the minor
 version-number is the second byte of the encoding.  The protocol
 described in [RFC8011] has a major version-number of 1 (0x01) and a
 minor version-number of 1 (0x01).  The ABNF for these two bytes is
 %x01.01.
 Note: See Section 9 for more information on the "version-number"
 field and IPP version numbers.

3.4.2. "operation-id"

 The "operation-id" field contains an operation-id value as defined in
 the Model.  The value is encoded as a SIGNED-SHORT and is located in
 the third and fourth bytes of the encoding of an operation request.

Sweet & McDonald Standards Track [Page 18] RFC 8010 IPP/1.1: Encoding and Transport January 2017

3.4.3. "status-code"

 The "status-code" field contains a status-code value as defined in
 the Model.  The value is encoded as a SIGNED-SHORT and is located in
 the third and fourth bytes of the encoding of an operation response.
 If an IPP status-code is returned, then the HTTP status-code MUST be
 200 (OK).  With any other HTTP status-code value, the HTTP response
 MUST NOT contain an IPP message body, and thus no IPP status-code is
 returned.

3.4.4. "request-id"

 The "request-id" field contains the request-id value as defined in
 the Model.  The value is encoded as a SIGNED-INTEGER and is located
 in the fifth through eighth bytes of the encoding.

3.5. Tags

 There are two kinds of tags:
 o  delimiter tags: delimit major sections of the protocol, namely
    attribute groups and data
 o  value tags: specify the type of each attribute value
 Tags are part of the IANA IPP registry [IANA-IPP]

3.5.1. "delimiter-tag" Values

 Table 2 specifies the values for the delimiter tags defined in this
 document.  These tags are registered, along with tags defined in
 other documents, in the "Attribute Group Tags" registry.
          +-----------------+------------------------------+
          | Tag Value (Hex) | Meaning                      |
          +-----------------+------------------------------+
          | 0x00            | Reserved                     |
          | 0x01            | "operation-attributes-tag"   |
          | 0x02            | "job-attributes-tag"         |
          | 0x03            | "end-of-attributes-tag"      |
          | 0x04            | "printer-attributes-tag"     |
          | 0x05            | "unsupported-attributes-tag" |
          +-----------------+------------------------------+
                    Table 2: "delimiter-tag" Values

Sweet & McDonald Standards Track [Page 19] RFC 8010 IPP/1.1: Encoding and Transport January 2017

 When a "begin-attribute-group-tag" field occurs in the protocol, it
 means that zero or more following attributes up to the next group tag
 are attributes belonging to the attribute group specified by the
 value of the "begin-attribute-group-tag".  For example, if the value
 of "begin-attribute-group-tag" is 0x01, the following attributes are
 members of the Operations Attributes group.
 The "end-of-attributes-tag" (value 0x03) MUST occur exactly once in
 an operation and MUST be the last "delimiter-tag".  If the operation
 has a document-data group, the Document data in that group follows
 the "end-of-attributes-tag".
 The order and presence of "attribute-group" fields (whose beginning
 is marked by the "begin-attribute-group-tag" subfield) for each
 operation request and each operation response MUST be that defined in
 the Model.
 A Printer MUST treat a "delimiter-tag" (values from 0x00 through
 0x0f) differently from a "value-tag" (values from 0x10 through 0xff)
 so that the Printer knows there is an entire attribute group as
 opposed to a single value.

3.5.2. "value-tag" Values

 The remaining tables show values for the "value-tag" field, which is
 the first octet of an attribute.  The "value-tag" field specifies the
 type of the value of the attribute.
 Table 3 specifies the "out-of-band" values for the "value-tag" field
 defined in this document.  These tags are registered, along with tags
 defined in other documents, in the "Out-of-Band Attribute Value Tags"
 registry.
                   +-----------------+-------------+
                   | Tag Value (Hex) | Meaning     |
                   +-----------------+-------------+
                   | 0x10            | unsupported |
                   | 0x12            | unknown     |
                   | 0x13            | no-value    |
                   +-----------------+-------------+
                      Table 3: Out-of-Band Values

Sweet & McDonald Standards Track [Page 20] RFC 8010 IPP/1.1: Encoding and Transport January 2017

 Table 4 specifies the integer values defined in this document for the
 "value-tag" field; they are registered in the "Attribute Syntaxes"
 registry.
 +----------------+--------------------------------------------------+
 | Tag Value      | Meaning                                          |
 | (Hex)          |                                                  |
 +----------------+--------------------------------------------------+
 | 0x20           | Unassigned integer data type (see IANA IPP       |
 |                | registry)                                        |
 | 0x21           | integer                                          |
 | 0x22           | boolean                                          |
 | 0x23           | enum                                             |
 | 0x24-0x2f      | Unassigned integer data types (see IANA IPP      |
 |                | registry)                                        |
 +----------------+--------------------------------------------------+
                         Table 4: Integer Tags
 Table 5 specifies the octetString values defined in this document for
 the "value-tag" field; they are registered in the "Attribute
 Syntaxes" registry.
 +---------------+---------------------------------------------------+
 | Tag Value     | Meaning                                           |
 | (Hex)         |                                                   |
 +---------------+---------------------------------------------------+
 | 0x30          | octetString with an unspecified format            |
 | 0x31          | dateTime                                          |
 | 0x32          | resolution                                        |
 | 0x33          | rangeOfInteger                                    |
 | 0x34          | begCollection                                     |
 | 0x35          | textWithLanguage                                  |
 | 0x36          | nameWithLanguage                                  |
 | 0x37          | endCollection                                     |
 | 0x38-0x3f     | Unassigned octetString data types (see IANA IPP   |
 |               | registry)                                         |
 +---------------+---------------------------------------------------+
                       Table 5: octetString Tags

Sweet & McDonald Standards Track [Page 21] RFC 8010 IPP/1.1: Encoding and Transport January 2017

 Table 6 specifies the character-string values defined in this
 document for the "value-tag" field; they are registered in the
 "Attribute Syntaxes" registry.
 +---------------+---------------------------------------------------+
 | Tag Value     | Meaning                                           |
 | (Hex)         |                                                   |
 +---------------+---------------------------------------------------+
 | 0x40          | Unassigned character-string data type (see IANA   |
 |               | IPP registry)                                     |
 | 0x41          | textWithoutLanguage                               |
 | 0x42          | nameWithoutLanguage                               |
 | 0x43          | Unassigned character-string data type (see IANA   |
 |               | IPP registry)                                     |
 | 0x44          | keyword                                           |
 | 0x45          | uri                                               |
 | 0x46          | uriScheme                                         |
 | 0x47          | charset                                           |
 | 0x48          | naturalLanguage                                   |
 | 0x49          | mimeMediaType                                     |
 | 0x4a          | memberAttrName                                    |
 | 0x4b-0x5f     | Unassigned character-string data types (see IANA  |
 |               | IPP registry)                                     |
 +---------------+---------------------------------------------------+
                         Table 6: String Tags
 Note: An attribute value always has a type, which is explicitly
 specified by its tag; one such tag value is "nameWithoutLanguage".
 An attribute's name has an implicit type, which is keyword.
 The values 0x60-0xff are reserved for future type definitions in
 Standards Track documents.
 The tag 0x7f is reserved for extending types beyond the 255 values
 available with a single byte.  A tag value of 0x7f MUST signify that
 the first four bytes of the value field are interpreted as the tag
 value.  Note this future extension doesn't affect parsers that are
 unaware of this special tag.  The tag is like any other unknown tag,
 and the value length specifies the length of a value, which contains
 a value that the parser treats atomically.  Values from 0x00000000 to
 0x3fffffff are reserved for definition in future Standards Track
 documents.  The values 0x40000000 to 0x7fffffff are reserved for
 vendor extensions.

Sweet & McDonald Standards Track [Page 22] RFC 8010 IPP/1.1: Encoding and Transport January 2017

3.6. "name-length"

 The "name-length" field consists of a SIGNED-SHORT and specifies the
 number of octets in the immediately following "name" field.  The
 value of this field excludes the two bytes of the "name-length"
 field.  For example, if the "name" field contains 'sides', the value
 of this field is 5.
 If a "name-length" field has a value of zero, the following "name"
 field is empty and the following value is treated as an additional
 value for the attribute encoded in the nearest preceding "attribute-
 with-one-value" field.  Within an attribute group, if two or more
 attributes have the same name, the attribute group is malformed (see
 [RFC8011]).  The zero-length name is the only mechanism for multi-
 valued attributes.

3.7. (Attribute) "name"

 The "name" field contains the name of an attribute.  The Model
 specifies such names.

3.8. "value-length"

 The "value-length" field consists of a SIGNED-SHORT, which specifies
 the number of octets in the immediately following "value" field.  The
 value of this field excludes the two bytes of the "value-length"
 field.  For example, if the "value" field contains the keyword
 (string) value 'one-sided', the value of this field is 9.
 For any of the types represented by binary signed integers, the
 sender MUST encode the value in exactly four octets.
 For any of the types represented by binary signed bytes, e.g., the
 boolean type, the sender MUST encode the value in exactly one octet.
 For any of the types represented by character strings, the sender
 MUST encode the value with all the characters of the string and
 without any padding characters.
 For "out-of-band" values for the "value-tag" field defined in this
 document, such as 'unsupported', the "value-length" MUST be 0 and the
 "value" empty; the "value" has no meaning when the "value-tag" has
 one of these "out-of-band" values.  For future "out-of-band" "value-
 tag" fields, the same rule holds unless the definition explicitly
 states that the "value-length" MAY be non-zero and the "value" non-
 empty

Sweet & McDonald Standards Track [Page 23] RFC 8010 IPP/1.1: Encoding and Transport January 2017

3.9. (Attribute) "value"

 The syntax types (specified by the "value-tag" field) and most of the
 details of the representation of attribute values are defined in the
 Model.  Table 7 augments the information in the Model and defines the
 syntax types from the Model in terms of the five basic types defined
 in Section 3.  The five types are US-ASCII-STRING, LOCALIZED-STRING,
 SIGNED-INTEGER, SIGNED-SHORT, SIGNED-BYTE, and OCTET-STRING.
 +----------------------+--------------------------------------------+
 | Syntax of Attribute  | Encoding                                   |
 | Value                |                                            |
 +----------------------+--------------------------------------------+
 | textWithoutLanguage, | LOCALIZED-STRING                           |
 | nameWithoutLanguage  |                                            |
 +----------------------+--------------------------------------------+
 | textWithLanguage     | OCTET-STRING consisting of four fields: a  |
 |                      | SIGNED-SHORT, which is the number of       |
 |                      | octets in the following field; a value of  |
 |                      | type natural-language; a SIGNED-SHORT,     |
 |                      | which is the number of octets in the       |
 |                      | following field; and a value of type       |
 |                      | textWithoutLanguage.  The length of a      |
 |                      | textWithLanguage value MUST be 4 + the     |
 |                      | value of field a + the value of field c.   |
 +----------------------+--------------------------------------------+
 | nameWithLanguage     | OCTET-STRING consisting of four fields: a  |
 |                      | SIGNED-SHORT, which is the number of       |
 |                      | octets in the following field; a value of  |
 |                      | type natural-language; a SIGNED-SHORT,     |
 |                      | which is the number of octets in the       |
 |                      | following field; and a value of type       |
 |                      | nameWithoutLanguage.  The length of a      |
 |                      | nameWithLanguage value MUST be 4 + the     |
 |                      | value of field a + the value of field c.   |
 +----------------------+--------------------------------------------+
 | charset,             | US-ASCII-STRING                            |
 | naturalLanguage,     |                                            |
 | mimeMediaType,       |                                            |
 | keyword, uri, and    |                                            |
 | uriScheme            |                                            |
 +----------------------+--------------------------------------------+
 | boolean              | SIGNED-BYTE where 0x00 is 'false' and 0x01 |
 |                      | is 'true'                                  |
 +----------------------+--------------------------------------------+
 | integer and enum     | a SIGNED-INTEGER                           |

Sweet & McDonald Standards Track [Page 24] RFC 8010 IPP/1.1: Encoding and Transport January 2017

 +----------------------+--------------------------------------------+
 | dateTime             | OCTET-STRING consisting of eleven octets   |
 |                      | whose contents are defined by              |
 |                      | "DateAndTime" in RFC 2579 [RFC2579]        |
 +----------------------+--------------------------------------------+
 | resolution           | OCTET-STRING consisting of nine octets of  |
 |                      | two SIGNED-INTEGERs followed by a SIGNED-  |
 |                      | BYTE.  The first SIGNED-INTEGER contains   |
 |                      | the value of cross-feed direction          |
 |                      | resolution.  The second SIGNED-INTEGER     |
 |                      | contains the value of feed direction       |
 |                      | resolution.  The SIGNED-BYTE contains the  |
 |                      | units value.                               |
 +----------------------+--------------------------------------------+
 | rangeOfInteger       | Eight octets consisting of two SIGNED-     |
 |                      | INTEGERs.  The first SIGNED-INTEGER        |
 |                      | contains the lower bound and the second    |
 |                      | SIGNED-INTEGER contains the upper bound.   |
 +----------------------+--------------------------------------------+
 | 1setOf X             | Encoding according to the rules for an     |
 |                      | attribute with more than one value.  Each  |
 |                      | value X is encoded according to the rules  |
 |                      | for encoding its type.                     |
 +----------------------+--------------------------------------------+
 | octetString          | OCTET-STRING                               |
 +----------------------+--------------------------------------------+
 | collection           | Encoding as defined in Section 3.1.6.      |
 +----------------------+--------------------------------------------+
                   Table 7: Attribute Value Encoding
 The attribute syntax type of the value determines its encoding and
 the value of its "value-tag".

3.10. Data

 The "data" field MUST include any data required by the operation.

Sweet & McDonald Standards Track [Page 25] RFC 8010 IPP/1.1: Encoding and Transport January 2017

4. Encoding of Transport Layer

 HTTP/1.1 [RFC7230] is the REQUIRED transport layer for this protocol.
 HTTP/2 [RFC7540] is an OPTIONAL transport layer for this protocol.
 The operation layer has been designed with the assumption that the
 transport layer contains the following information:
 o  the target URI for the operation; and
 o  the total length of the data in the operation layer, either as a
    single length or as a sequence of chunks each with a length.
 Printer implementations MUST support HTTP over the IANA-assigned
 well-known port 631 (the IPP default port), although a Printer
 implementation can support HTTP over some other port as well.
 Each HTTP operation MUST use the POST method where the request-target
 is the object target of the operation and where the "Content-Type" of
 the message body in each request and response MUST be "application/
 ipp".  The message body MUST contain the operation layer and MUST
 have the syntax described in Section 3.2, "Syntax of Encoding".  A
 Client implementation MUST adhere to the rules for a Client described
 for HTTP [RFC7230].  A Printer (server) implementation MUST adhere to
 the rules for an origin server described for HTTP [RFC7230].
 An IPP server sends a response for each request that it receives.  If
 an IPP server detects an error, it MAY send a response before it has
 read the entire request.  If the HTTP layer of the IPP server
 completes processing the HTTP headers successfully, it MAY send an
 intermediate response, such as "100 Continue", with no IPP data
 before sending the IPP response.  A Client MUST expect such a variety
 of responses from an IPP server.  For further information on HTTP,
 consult the HTTP documents [RFC7230].
 An HTTP/1.1 server MUST support chunking for IPP requests, and an IPP
 Client MUST support chunking for IPP responses according to HTTP/1.1
 [RFC7230].

4.1. Printer URI, Job URI, and Job ID

 All Printer and Job objects are identified by a Uniform Resource
 Identifier (URI) [RFC3986] so that they can be persistently and
 unambiguously referenced.  Jobs can also be identified by a
 combination of Printer URI and Job ID.

Sweet & McDonald Standards Track [Page 26] RFC 8010 IPP/1.1: Encoding and Transport January 2017

 Some operation elements are encoded twice, once as the request-target
 on the HTTP request-line and a second time as a REQUIRED operation
 attribute in the application/ipp entity.  These attributes are the
 target for the operation and are called "printer-uri" and "job-uri".
 Note: The target URI is included twice in an operation referencing
 the same IPP object, but the two URIs can be different.  For example,
 the HTTP request-target can be relative while the IPP request URI is
 absolute.
 HTTP allows Clients to generate and send a relative URI rather than
 an absolute URI.  A relative URI identifies a resource with the scope
 of the HTTP server but does not include scheme, host, or port.  The
 following statements characterize how URIs are used in the mapping of
 IPP onto HTTP:
 1.  Although potentially redundant, a Client MUST supply the target
     of the operation both as an operation attribute and as a URI at
     the HTTP layer.  The rationale for this decision is to maintain a
     consistent set of rules for mapping "application/ipp" to possibly
     many communication layers, even where URIs are not used as the
     addressing mechanism in the transport layer.
 2.  Even though these two URIs might not be literally identical (one
     being relative and the other being absolute), they MUST both
     reference the same IPP object.
 3.  The URI in the HTTP layer is either relative or absolute and is
     used by the HTTP server to route the HTTP request to the correct
     resource relative to that HTTP server.
 4.  Once the HTTP server resource begins to process the HTTP request,
     it can get the reference to the appropriate IPP Printer object
     from either the HTTP URI (using to the context of the HTTP server
     for relative URIs) or from the URI within the operation request;
     the choice is up to the implementation.
 5.  HTTP URIs can be relative or absolute, but the target URI in the
     IPP operation attribute MUST be an absolute URI.

Sweet & McDonald Standards Track [Page 27] RFC 8010 IPP/1.1: Encoding and Transport January 2017

5. IPP URI Schemes

 The IPP URI schemes are 'ipp' [RFC3510] and 'ipps' [RFC7472].
 Clients and Printers MUST support the ipp-URI value in the following
 IPP attributes:
 o  Job attributes:
  • job-uri
  • job-printer-uri
 o  Printer attributes:
  • printer-uri-supported
 o  Operation attributes:
  • job-uri
  • printer-uri
 Each of the above attributes identifies a Printer or Job.  The
 ipp-URI and ipps-URI are intended as the value of the attributes in
 this list.  All of these attributes have a syntax type of 'uri', but
 there are attributes with a syntax type of 'uri' that do not use the
 'ipp' scheme, e.g., "job-more-info".
 If a Printer registers its URI with a directory service, the Printer
 MUST register an ipp-URI or ipps-URI.
 When a Client sends a request, it MUST convert a target ipp-URI to a
 target http-URL (or ipps-URI to a target https-URI) for the HTTP
 layer according to the following steps:
 1.  change the 'ipp' scheme to 'http' or 'ipps' scheme to 'https';
     and
 2.  add an explicit port 631 if the ipp-URL or ipps-URL does not
     contain an explicit port.  Note that port 631 is the IANA-
     assigned well-known port for the 'ipp' and 'ipps' schemes.
 The Client MUST use the target http-URL or https-URL in both the HTTP
 request-line and HTTP headers, as specified by HTTP [RFC7230].
 However, the Client MUST use the target ipp-URI or ipps-URI for the
 value of the "printer-uri" or "job-uri" operation attribute within
 the application/ipp body of the request.  The server MUST use the

Sweet & McDonald Standards Track [Page 28] RFC 8010 IPP/1.1: Encoding and Transport January 2017

 ipp-URI or ipps-URI for the value of the "printer-uri", "job-uri", or
 "printer-uri-supported" attributes within the application/ipp body of
 the response.
 For example, when an IPP Client sends a request directly, i.e., no
 proxy, to an ipp-URI "ipp://printer.example.com/ipp/print/myqueue",
 it opens a TCP connection to port 631 (the IPP implicit port) on the
 host "printer.example.com" and sends the following data:
   POST /ipp/print/myqueue HTTP/1.1
   Host: printer.example.com:631
   Content-type: application/ipp
   Transfer-Encoding: chunked
   ...
   "printer-uri" 'ipp://printer.example.com/ipp/print/myqueue'
          (encoded in application/ipp message body)
   ...
                     Figure 11: Direct IPP Request
 As another example, when an IPP Client sends the same request as
 above via a proxy "myproxy.example.com", it opens a TCP connection to
 the proxy port 8080 on the proxy host "myproxy.example.com" and sends
 the following data:
   POST http://printer.example.com:631/ipp/print/myqueue HTTP/1.1
   Host: printer.example.com:631
   Content-type: application/ipp
   Transfer-Encoding: chunked
   ...
   "printer-uri" 'ipp://printer.example.com/ipp/print/myqueue'
          (encoded in application/ipp message body)
   ...
                    Figure 12: Proxied IPP Request
 The proxy then connects to the IPP origin server with headers that
 are the same as the "no-proxy" example above.

6. IANA Considerations

 The IANA-PRINTER-MIB [RFC3805] has been updated to reference this
 document; the current version is available from
 <http://www.iana.org>.
 See the IANA Considerations in the document "Internet Printing
 Protocol/1.1: Model and Semantics" [RFC8011] for information on IANA
 considerations for IPP extensions.  IANA has updated the existing

Sweet & McDonald Standards Track [Page 29] RFC 8010 IPP/1.1: Encoding and Transport January 2017

 'application/ipp' media type registration (whose contents are defined
 in Section 3 "Encoding of the Operation Layer") with the following
 information.
 Type name: application
 Subtype name: ipp
 Required parameters: N/A
 Optional parameters: N/A
 Encoding considerations: IPP requests/responses MAY contain long
 lines and ALWAYS contain binary data (for example, attribute value
 lengths).
 Security considerations: IPP requests/responses do not introduce any
 security risks not already inherent in the underlying transport
 protocols.  Protocol mixed-version interworking rules in [RFC8011] as
 well as protocol-encoding rules in this document are complete and
 unambiguous.  See also the security considerations in this document
 and [RFC8011].
 Interoperability considerations: IPP requests (generated by Clients)
 and responses (generated by servers) MUST comply with all conformance
 requirements imposed by the normative specifications [RFC8011] and
 this document.  Protocol-encoding rules specified in RFC 8010 are
 comprehensive so that interoperability between conforming
 implementations is guaranteed (although support for specific optional
 features is not ensured).  Both the "charset" and "natural-language"
 of all IPP attribute values that are a LOCALIZED-STRING are explicit
 within IPP requests/responses (without recourse to any external
 information in HTTP, SMTP, or other message transport headers).
 Published specifications: RFCs 8010 and 8011
 Applications that use this media type: Internet Printing Protocol
 (IPP) print clients and print servers that communicate using HTTP/
 HTTPS or other transport protocols.  Messages of type "application/
 ipp" are self-contained and transport independent, including
 "charset" and "natural-language" context for any LOCALIZED-STRING
 value.
 Fragment identifier considerations: N/A

Sweet & McDonald Standards Track [Page 30] RFC 8010 IPP/1.1: Encoding and Transport January 2017

 Additional information:
    Deprecated alias names for this type: N/A
    Magic number(s): N/A
    File extension(s): N/A
    Macintosh file type code(s): N/A
 Person & email address to contact for further information:
    ISTO PWG IPP Workgroup <ipp@pwg.org>
 Intended usage: COMMON
 Restrictions on usage: N/A
 Author: ISTO PWG IPP Workgroup <ipp@pwg.org>
 Change controller: ISTO PWG IPP Workgroup <ipp@pwg.org>
 Provisional registration? (standards tree only): No

7. Internationalization Considerations

 See the section on "Internationalization Considerations" in the
 document "Internet Printing Protocol/1.1: Model and Semantics"
 [RFC8011] for information on internationalization.  This document
 adds no additional issues.

8. Security Considerations

 The IPP Model and Semantics document [RFC8011] discusses high-level
 security requirements (Client Authentication, Server Authentication,
 and Operation Privacy).  Client Authentication is the mechanism by
 which the Client proves its identity to the server in a secure
 manner.  Server Authentication is the mechanism by which the server
 proves its identity to the Client in a secure manner.  Operation
 Privacy is defined as a mechanism for protecting operations from
 eavesdropping.
 Message Integrity is addressed in the document "Internet Printing
 Protocol (IPP) over HTTPS Transport Binding and the 'ipps' URI
 Scheme" [RFC7472].

8.1. Security Conformance Requirements

 This section defines the security requirements for IPP Clients and
 IPP objects.

Sweet & McDonald Standards Track [Page 31] RFC 8010 IPP/1.1: Encoding and Transport January 2017

8.1.1. Digest Authentication

 IPP Clients and Printers SHOULD support Digest Authentication
 [RFC7616].  Use of the Message Integrity feature (qop="auth-int") is
 OPTIONAL.
 Note: Previous versions of this specification required support for
 the MD5 algorithms; however, [RFC7616] makes SHA2-256 mandatory to
 implement and deprecates MD5, only allowing its use for backwards
 compatibility reasons.  IPP implementations that support Digest
 Authentication MUST support SHA2-256 and SHOULD support MD5 for
 backwards compatibility.
 Note: The reason that IPP Clients and Printers SHOULD (rather than
 MUST) support Digest Authentication is that there is a certain class
 of Output Devices where it does not make sense.  Specifically, a low-
 end device with limited ROM space and low paper throughput may not
 need Client Authentication.  This class of device typically requires
 firmware designers to make trade-offs between protocols and
 functionality to arrive at the lowest-cost solution possible.
 Factored into the designer's decisions is not just the size of the
 code, but also the testing, maintenance, usefulness, and time-to-
 market impact for each feature delivered to the customer.  Forcing
 such low-end devices to provide security in order to claim IPP/1.1
 conformance would not make business sense.  Print devices that have
 high-volume throughput and have available ROM space will typically
 provide support for Client Authentication that safeguards the device
 from unauthorized access because these devices are prone to a high
 loss of consumables and paper if unauthorized access occurs.

8.1.2. Transport Layer Security (TLS)

 IPP Clients and Printers SHOULD support Transport Layer Security
 (TLS) [RFC5246] [RFC7525] for Server Authentication and Operation
 Privacy.  IPP Printers MAY also support TLS for Client
 Authentication.  IPP Clients and Printers MAY support Basic
 Authentication [RFC7617] for User Authentication if the channel is
 secure, e.g., IPP over HTTPS [RFC7472].  IPP Clients and Printers
 SHOULD NOT support Basic Authentication over insecure channels.
 The IPP Model and Semantics document [RFC8011] defines two Printer
 attributes ("uri-authentication-supported" and "uri-security-
 supported") that the Client can use to discover the security policy
 of a Printer.  That document also outlines IPP-specific security
 considerations and is the primary reference for security implications
 with regard to the IPP itself.

Sweet & McDonald Standards Track [Page 32] RFC 8010 IPP/1.1: Encoding and Transport January 2017

 Note: Because previous versions of this specification did not require
 TLS support, this version cannot require it for IPP/1.1.  However,
 since printing often involves a great deal of sensitive or private
 information (medical reports, performance reviews, banking
 information, etc.) and network monitoring is pervasive ([RFC7258]),
 implementors are strongly encouraged to include TLS support.
 Note: Because IPP Printers typically use self-signed X.509
 certificates, IPP Clients SHOULD support Trust On First Use (defined
 in [RFC7435]) in addition to traditional X.509 certificate
 validation.

8.2. Using IPP with TLS

 IPP uses the "Upgrading to TLS Within HTTP/1.1" mechanism [RFC2817]
 for 'ipp' URIs.  The Client requests a secure TLS connection by using
 the HTTP "Upgrade" header while the server agrees in the HTTP
 response.  The switch to TLS occurs either because the server grants
 the Client's request to upgrade to TLS or a server asks to switch to
 TLS in its response.  Secure communication begins with a server's
 response to switch to TLS.
 IPP uses the "HTTPS: HTTP over TLS" mechanism [RFC2818] for 'ipps'
 URIs.  The Client and server negotiate a secure TLS connection
 immediately and unconditionally.

9. Interoperability with Other IPP Versions

 It is beyond the scope of this specification to mandate conformance
 with versions of IPP other than 1.1.  IPP was deliberately designed,
 however, to make supporting other versions easy.  IPP objects
 (Printers, Jobs, etc.) SHOULD:
 o  understand any valid request whose major "version-number" is
    greater than 0; and
 o  respond appropriately with a response containing the same
    "version-number" parameter value used by the Client in the request
    (if the Client-supplied "version-number" is supported) or the
    highest "version-number" supported by the Printer (if the Client-
    supplied "version-number" is not supported).
 IPP Clients SHOULD:
 o  understand any valid response whose major "version-number" is
    greater than 0.

Sweet & McDonald Standards Track [Page 33] RFC 8010 IPP/1.1: Encoding and Transport January 2017

9.1. The "version-number" Parameter

 The following are rules regarding the "version-number" parameter (see
 Section 3.3):
 1.  Clients MUST send requests containing a "version-number"
     parameter with the highest supported value, e.g., '1.1', '2.0',
     etc., and SHOULD try supplying alternate version numbers if they
     receive a 'server-error-version-not-supported' error return in a
     response.  For example, if a Client sends an IPP/2.0 request that
     is rejected with the 'server-error-version-not-supported' error
     and an IPP/1.1 "version-number", it SHOULD retry by sending an
     IPP/1.1 request.
 2.  IPP objects (Printers, Jobs, etc.)  MUST accept requests
     containing a "version-number" parameter with a '1.1' value (or
     reject the request for reasons other than 'server-error-version-
     not-supported').
 3.  IPP objects SHOULD either accept requests whose major version is
     greater than 0 or reject such requests with the 'server-error-
     version-not-supported' status-code.  See Section 4.1.8 of
     [RFC8011].
 4.  In any case, security MUST NOT be compromised when a Client
     supplies a lower "version-number" parameter in a request.  For
     example, if an IPP/2.0 conforming Printer accepts version '1.1'
     requests and is configured to enforce Digest Authentication, it
     MUST do the same for a version '1.1' request.

9.2. Security and URI Schemes

 The following are rules regarding security, the "version-number"
 parameter, and the URI scheme supplied in target attributes and
 responses:
 1.  When a Client supplies a request, the "printer-uri" or "job-uri"
     target operation attribute MUST have the same scheme as that
     indicated in one of the values of the "printer-uri-supported"
     Printer attribute.
 2.  When the Printer returns the "job-printer-uri" or "job-uri" Job
     Description attributes, it SHOULD return the same scheme ('ipp',
     'ipps', etc.) that the Client supplied in the "printer-uri" or
     "job-uri" target operation attributes in the Get-Job-Attributes
     or Get-Jobs request, rather than the scheme used when the Job was
     created.  However, when a Client requests Job attributes using
     the Get-Job-Attributes or Get-Jobs operations, the Jobs and Job

Sweet & McDonald Standards Track [Page 34] RFC 8010 IPP/1.1: Encoding and Transport January 2017

     attributes that the Printer returns depends on: (1) the security
     in effect when the Job was created, (2) the security in effect in
     the query request, and (3) the security policy in force.
 3.  The Printer MUST enforce its security and privacy policies based
     on the owner of the IPP object and the URI scheme and/or
     credentials supplied by the Client in the current request.

10. Changes since RFC 2910

 The following changes have been made since the publication of
 RFC 2910:
 o  Added references to current IPP extension specifications.
 o  Added optional support for HTTP/2.
 o  Added collection attribute syntax from RFC 3382.
 o  Fixed typographical errors.
 o  Now reference TLS/1.2 and no longer mandate the TLS/1.0 MTI
    ciphersuites.
 o  Updated all references.
 o  Updated document organization to follow current style.
 o  Updated example ipp: URIs to follow guidelines in RFC 7472.
 o  Updated version compatibility for all versions of IPP.
 o  Updated HTTP Digest Authentication to optional for Clients.
 o  Removed references to (Experimental) IPP/1.0 and usage of
    http:/https: URLs.

Sweet & McDonald Standards Track [Page 35] RFC 8010 IPP/1.1: Encoding and Transport January 2017

11. References

11.1. Normative References

 [PWG5100.12]
            Sweet, M. and I. McDonald, "IPP Version 2.0, 2.1, and
            2.2", October 2015, <http://ftp.pwg.org/pub/pwg/standards/
            std-ipp20-20151030-5100.12.pdf>.
 [RFC20]    Cerf, V., "ASCII format for network interchange", STD 80,
            RFC 20, DOI 10.17487/RFC0020, October 1969,
            <http://www.rfc-editor.org/info/rfc20>.
 [RFC793]   Postel, J., "Transmission Control Protocol", STD 7,
            RFC 793, DOI 10.17487/RFC0793, September 1981,
            <http://www.rfc-editor.org/info/rfc793>.
 [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
            Requirement Levels", BCP 14, RFC 2119,
            DOI 10.17487/RFC2119, March 1997,
            <http://www.rfc-editor.org/info/rfc2119>.
 [RFC2579]  McCloghrie, K., Ed., Perkins, D., Ed., and J.
            Schoenwaelder, Ed., "Textual Conventions for SMIv2",
            STD 58, RFC 2579, DOI 10.17487/RFC2579, April 1999,
            <http://www.rfc-editor.org/info/rfc2579>.
 [RFC2817]  Khare, R. and S. Lawrence, "Upgrading to TLS Within
            HTTP/1.1", RFC 2817, DOI 10.17487/RFC2817, May 2000,
            <http://www.rfc-editor.org/info/rfc2817>.
 [RFC2818]  Rescorla, E., "HTTP Over TLS", RFC 2818,
            DOI 10.17487/RFC2818, May 2000,
            <http://www.rfc-editor.org/info/rfc2818>.
 [RFC2978]  Freed, N. and J. Postel, "IANA Charset Registration
            Procedures", BCP 19, RFC 2978, DOI 10.17487/RFC2978,
            October 2000, <http://www.rfc-editor.org/info/rfc2978>.
 [RFC3510]  Herriot, R. and I. McDonald, "Internet Printing
            Protocol/1.1: IPP URL Scheme", RFC 3510,
            DOI 10.17487/RFC3510, April 2003,
            <http://www.rfc-editor.org/info/rfc3510>.
 [RFC3629]  Yergeau, F., "UTF-8, a transformation format of ISO
            10646", STD 63, RFC 3629, DOI 10.17487/RFC3629, November
            2003, <http://www.rfc-editor.org/info/rfc3629>.

Sweet & McDonald Standards Track [Page 36] RFC 8010 IPP/1.1: Encoding and Transport January 2017

 [RFC3986]  Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
            Resource Identifier (URI): Generic Syntax", STD 66,
            RFC 3986, DOI 10.17487/RFC3986, January 2005,
            <http://www.rfc-editor.org/info/rfc3986>.
 [RFC5234]  Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
            Specifications: ABNF", STD 68, RFC 5234,
            DOI 10.17487/RFC5234, January 2008,
            <http://www.rfc-editor.org/info/rfc5234>.
 [RFC5246]  Dierks, T. and E. Rescorla, "The Transport Layer Security
            (TLS) Protocol Version 1.2", RFC 5246,
            DOI 10.17487/RFC5246, August 2008,
            <http://www.rfc-editor.org/info/rfc5246>.
 [RFC7230]  Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
            Protocol (HTTP/1.1): Message Syntax and Routing",
            RFC 7230, DOI 10.17487/RFC7230, June 2014,
            <http://www.rfc-editor.org/info/rfc7230>.
 [RFC7231]  Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
            Protocol (HTTP/1.1): Semantics and Content", RFC 7231,
            DOI 10.17487/RFC7231, June 2014,
            <http://www.rfc-editor.org/info/rfc7231>.
 [RFC7232]  Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
            Protocol (HTTP/1.1): Conditional Requests", RFC 7232,
            DOI 10.17487/RFC7232, June 2014,
            <http://www.rfc-editor.org/info/rfc7232>.
 [RFC7234]  Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
            Ed., "Hypertext Transfer Protocol (HTTP/1.1): Caching",
            RFC 7234, DOI 10.17487/RFC7234, June 2014,
            <http://www.rfc-editor.org/info/rfc7234>.
 [RFC7235]  Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
            Protocol (HTTP/1.1): Authentication", RFC 7235,
            DOI 10.17487/RFC7235, June 2014,
            <http://www.rfc-editor.org/info/rfc7235>.
 [RFC7472]  McDonald, I. and M. Sweet, "Internet Printing Protocol
            (IPP) over HTTPS Transport Binding and the 'ipps' URI
            Scheme", RFC 7472, DOI 10.17487/RFC7472, March 2015,
            <http://www.rfc-editor.org/info/rfc7472>.

Sweet & McDonald Standards Track [Page 37] RFC 8010 IPP/1.1: Encoding and Transport January 2017

 [RFC7540]  Belshe, M., Peon, R., and M. Thomson, Ed., "Hypertext
            Transfer Protocol Version 2 (HTTP/2)", RFC 7540,
            DOI 10.17487/RFC7540, May 2015,
            <http://www.rfc-editor.org/info/rfc7540>.
 [RFC7541]  Peon, R. and H. Ruellan, "HPACK: Header Compression for
            HTTP/2", RFC 7541, DOI 10.17487/RFC7541, May 2015,
            <http://www.rfc-editor.org/info/rfc7541>.
 [RFC7616]  Shekh-Yusef, R., Ed., Ahrens, D., and S. Bremer, "HTTP
            Digest Access Authentication", RFC 7616,
            DOI 10.17487/RFC7616, September 2015,
            <http://www.rfc-editor.org/info/rfc7616>.
 [RFC7617]  Reschke, J., "The 'Basic' HTTP Authentication Scheme",
            RFC 7617, DOI 10.17487/RFC7617, September 2015,
            <http://www.rfc-editor.org/info/rfc7617>.
 [RFC8011]  Sweet, M. and I. McDonald, "Internet Printing
            Protocol/1.1: Model and Semantics", RFC 8011,
            DOI 10.17487/RFC8011, January 2017,
            <http://www.rfc-editor.org/info/rfc8011>.

11.2. Informative References

 [IANA-IPP] IANA, "Internet Printing Protocol (IPP) Registry",
            <http://www.iana.org/assignments/ipp-registrations/>.
 [PWG5100.3]
            Ocke, K. and T. Hastings, "Internet Printing Protocol
            (IPP): Production Printing Attributes - Set1", Candidate
            Standard 5100.3-2001, February 2001,
            <http://ftp.pwg.org/pub/pwg/candidates/
            cs-ippprodprint10-20010212-5100.3.pdf>.
 [RFC1179]  McLaughlin, L., "Line printer daemon protocol", RFC 1179,
            DOI 10.17487/RFC1179, August 1990,
            <http://www.rfc-editor.org/info/rfc1179>.
 [RFC7258]  Farrell, S. and H. Tschofenig, "Pervasive Monitoring Is an
            Attack", BCP 188, RFC 7258, DOI 10.17487/RFC7258, May
            2014, <http://www.rfc-editor.org/info/rfc7258>.
 [RFC7435]  Dukhovni, V., "Opportunistic Security: Some Protection
            Most of the Time", RFC 7435, DOI 10.17487/RFC7435,
            December 2014, <http://www.rfc-editor.org/info/rfc7435>.

Sweet & McDonald Standards Track [Page 38] RFC 8010 IPP/1.1: Encoding and Transport January 2017

 [RFC7525]  Sheffer, Y., Holz, R., and P. Saint-Andre,
            "Recommendations for Secure Use of Transport Layer
            Security (TLS) and Datagram Transport Layer Security
            (DTLS)", BCP 195, RFC 7525, DOI 10.17487/RFC7525, May
            2015, <http://www.rfc-editor.org/info/rfc7525>.

Sweet & McDonald Standards Track [Page 39] RFC 8010 IPP/1.1: Encoding and Transport January 2017

Appendix A. Protocol Examples

A.1. Print-Job Request

 The following is an example of a Print-Job request with "job-name",
 "copies", and "sides" specified.  The "ipp-attribute-fidelity"
 attribute is set to 'true' so that the print request will fail if the
 "copies" or the "sides" attribute is not supported or their values
 are not supported.
  Octets                         Symbolic Value       Protocol field
  0x0101                         1.1                  version-number
  0x0002                         Print-Job            operation-id
  0x00000001                     1                    request-id
  0x01                           start operation-     operation-
                                 attributes           attributes-tag
  0x47                           charset type         value-tag
  0x0012                                              name-length
  attributes-charset             attributes-charset   name
  0x0005                                              value-length
  utf-8                          UTF-8                value
  0x48                           natural-language     value-tag
                                 type
  0x001b                                              name-length
  attributes-natural-language    attributes-natural-  name
                                 language
  0x0005                                              value-length
  en-us                          en-US                value
  0x45                           uri type             value-tag
  0x000b                                              name-length
  printer-uri                    printer-uri          name
  0x002c                                              value-length
  ipp://printer.example.com/ipp/ printer pinetree     value
  print/pinetree
  0x42                           nameWithoutLanguage  value-tag
                                 type
  0x0008                                              name-length
  job-name                       job-name             name
  0x0006                                              value-length
  foobar                         foobar               value
  0x22                           boolean type         value-tag
  0x0016                                              name-length
  ipp-attribute-fidelity         ipp-attribute-       name
                                 fidelity
  0x0001                                              value-length
  0x01                           true                 value
  0x02                           start job-attributes job-attributes-

Sweet & McDonald Standards Track [Page 40] RFC 8010 IPP/1.1: Encoding and Transport January 2017

                                                      tag
  0x21                           integer type         value-tag
  0x0006                                              name-length
  copies                         copies               name
  0x0004                                              value-length
  0x00000014                     20                   value
  0x44                           keyword type         value-tag
  0x0005                                              name-length
  sides                          sides                name
  0x0013                                              value-length
  two-sided-long-edge            two-sided-long-edge  value
  0x03                           end-of-attributes    end-of-
                                                      attributes-tag
  %!PDF...                       <PDF Document>       data

A.2. Print-Job Response (Successful)

 Here is an example of a successful Print-Job response to the previous
 Print-Job request.  The Printer supported the "copies" and "sides"
 attributes and their supplied values.  The status-code returned is
 'successful-ok'.
  Octets                           Symbolic Value     Protocol field
  0x0101                           1.1                version-number
  0x0000                           successful-ok      status-code
  0x00000001                       1                  request-id
  0x01                             start operation-   operation-
                                   attributes         attributes-tag
  0x47                             charset type       value-tag
  0x0012                                              name-length
  attributes-charset               attributes-charset name
  0x0005                                              value-length
  utf-8                            UTF-8              value
  0x48                             natural-language   value-tag
                                   type
  0x001b                                              name-length
  attributes-natural-language      attributes-        name
                                   natural-language
  0x0005                                              value-length
  en-us                            en-US              value
  0x41                             textWithoutLanguag value-tag
                                   e type
  0x000e                                              name-length
  status-message                   status-message     name
  0x000d                                              value-length
  successful-ok                    successful-ok      value
  0x02                             start job-         job-attributes-

Sweet & McDonald Standards Track [Page 41] RFC 8010 IPP/1.1: Encoding and Transport January 2017

                                   attributes         tag
  0x21                             integer            value-tag
  0x0006                                              name-length
  job-id                           job-id             name
  0x0004                                              value-length
  147                              147                value
  0x45                             uri type           value-tag
  0x0007                                              name-length
  job-uri                          job-uri            name
  0x0030                                              value-length
  ipp://printer.example.com/ipp/pr job 147 on         value
  int/pinetree/147                 pinetree
  0x23                             enum type          value-tag
  0x0009                                              name-length
  job-state                        job-state          name
  0x0004                                              value-length
  0x0003                           pending            value
  0x03                             end-of-attributes  end-of-
                                                      attributes-tag

A.3. Print-Job Response (Failure)

 Here is an example of an unsuccessful Print-Job response to the
 previous Print-Job request.  It fails because, in this case, the
 Printer does not support the "sides" attribute and because the value
 '20' for the "copies" attribute is not supported.  Therefore, no Job
 is created, and neither a "job-id" nor a "job-uri" operation
 attribute is returned.  The error code returned is 'client-error-
 attributes-or-values-not-supported' (0x040b).
 Octets                      Symbolic Value              Protocol
                                                         field
 0x0101                      1.1                         version-
                                                         number
 0x040b                      client-error-attributes-or- status-code
                             values-not-supported
 0x00000001                  1                           request-id
 0x01                        start operation-attributes  operation-
                                                         attributes
                                                         tag
 0x47                        charset type                value-tag
 0x0012                                                  name-length
 attributes-charset          attributes-charset          name
 0x0005                                                  value-length
 utf-8                       UTF-8                       value
 0x48                        natural-language type       value-tag
 0x001b                                                  name-length

Sweet & McDonald Standards Track [Page 42] RFC 8010 IPP/1.1: Encoding and Transport January 2017

 attributes-natural-language attributes-natural-language name
 0x0005                                                  value-length
 en-us                       en-US                       value
 0x41                        textWithoutLanguage type    value-tag
 0x000e                                                  name-length
 status-message              status-message              name
 0x002f                                                  value-length
 client-error-attributes-or- client-error-attributes-or- value
 values-not-supported        values-not-supported
 0x05                        start unsupported-          unsupported-
                             attributes                  attributes
                                                         tag
 0x21                        integer type                value-tag
 0x0006                                                  name-length
 copies                      copies                      name
 0x0004                                                  value-length
 0x00000014                  20                          value
 0x10                        unsupported (type)          value-tag
 0x0005                                                  name-length
 sides                       sides                       name
 0x0000                                                  value-length
 0x03                        end-of-attributes           end-of-
                                                         attributes-
                                                         tag

A.4. Print-Job Response (Success with Attributes Ignored)

 Here is an example of a successful Print-Job response to a Print-Job
 request like the previous Print-Job request, except that the value of
 "ipp-attribute-fidelity" is 'false'.  The print request succeeds,
 even though, in this case, the Printer supports neither the "sides"
 attribute nor the value '20' for the "copies" attribute.  Therefore,
 a Job is created and both a "job-id" and a "job-uri" operation
 attribute are returned.  The unsupported attributes are also returned
 in an Unsupported Attributes group.  The error code returned is
 'successful-ok-ignored-or-substituted-attributes' (0x0001).
 Octets                     Symbolic Value              Protocol field
 0x0101                     1.1                         version-number
 0x0001                     successful-ok-ignored-or-   status-code
                            substituted-attributes
 0x00000001                 1                           request-id
 0x01                       start operation-attributes  operation-
                                                        attributes-tag
 0x47                       charset type                value-tag
 0x0012                                                 name-length
 attributes-charset         attributes-charset          name

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 0x0005                                                 value-length
 utf-8                      UTF-8                       value
 0x48                       natural-language type       value-tag
 0x001b                                                 name-length
 attributes-natural-        attributes-natural-language name
 language
 0x0005                                                 value-length
 en-us                      en-US                       value
 0x41                       textWithoutLanguage type    value-tag
 0x000e                                                 name-length
 status-message             status-message              name
 0x002f                                                 value-length
 successful-ok-ignored-or-  successful-ok-ignored-or-   value
 substituted-attributes     substituted-attributes
 0x05                       start unsupported-          unsupported-
                            attributes                  attributes tag
 0x21                       integer type                value-tag
 0x0006                                                 name-length
 copies                     copies                      name
 0x0004                                                 value-length
 0x00000014                 20                          value
 0x10                       unsupported  (type)         value-tag
 0x0005                                                 name-length
 sides                      sides                       name
 0x0000                                                 value-length
 0x02                       start job-attributes        job-
                                                        attributes-tag
 0x21                       integer                     value-tag
 0x0006                                                 name-length
 job-id                     job-id                      name
 0x0004                                                 value-length
 147                        147                         value
 0x45                       uri type                    value-tag
 0x0007                                                 name-length
 job-uri                    job-uri                     name
 0x0030                                                 value-length
 ipp://printer.example.com/ job 147 on pinetree         value
 ipp/print/pinetree/147
 0x23                       enum  type                  value-tag
 0x0009                                                 name-length
 job-state                  job-state                   name
 0x0004                                                 value-length
 0x0003                     pending                     value
 0x03                       end-of-attributes           end-of-
                                                        attributes-tag

Sweet & McDonald Standards Track [Page 44] RFC 8010 IPP/1.1: Encoding and Transport January 2017

A.5. Print-URI Request

 The following is an example of Print-URI request with "copies" and
 "job-name" parameters:
  Octets                         Symbolic Value       Protocol field
  0x0101                         1.1                  version-number
  0x0003                         Print-URI            operation-id
  0x00000001                     1                    request-id
  0x01                           start operation-     operation-
                                 attributes           attributes-tag
  0x47                           charset type         value-tag
  0x0012                                              name-length
  attributes-charset             attributes-charset   name
  0x0005                                              value-length
  utf-8                          UTF-8                value
  0x48                           natural-language     value-tag
                                 type
  0x001b                                              name-length
  attributes-natural-language    attributes-natural-  name
                                 language
  0x0005                                              value-length
  en-us                          en-US                value
  0x45                           uri type             value-tag
  0x000b                                              name-length
  printer-uri                    printer-uri          name
  0x002c                                              value-length
  ipp://printer.example.com/ipp/ printer pinetree     value
  print/pinetree
  0x45                           uri type             value-tag
  0x000c                                              name-length
  document-uri                   document-uri         name
  0x0019                                              value-length
  ftp://foo.example.com/foo      ftp://foo.example.co value
                                 m/foo
  0x42                           nameWithoutLanguage  value-tag
                                 type
  0x0008                                              name-length
  job-name                       job-name             name
  0x0006                                              value-length
  foobar                         foobar               value
  0x02                           start job-attributes job-attributes-
                                                      tag
  0x21                           integer type         value-tag
  0x0006                                              name-length
  copies                         copies               name
  0x0004                                              value-length

Sweet & McDonald Standards Track [Page 45] RFC 8010 IPP/1.1: Encoding and Transport January 2017

  0x00000001                     1                    value
  0x03                           end-of-attributes    end-of-
                                                      attributes-tag

A.6. Create-Job Request

 The following is an example of Create-Job request with no parameters
 and no attributes:
  Octets                         Symbolic Value       Protocol field
  0x0101                         1.1                  version-number
  0x0005                         Create-Job           operation-id
  0x00000001                     1                    request-id
  0x01                           start operation-     operation-
                                 attributes           attributes-tag
  0x47                           charset type         value-tag
  0x0012                                              name-length
  attributes-charset             attributes-charset   name
  0x0005                                              value-length
  utf-8                          UTF-8                value
  0x48                           natural-language     value-tag
                                 type
  0x001b                                              name-length
  attributes-natural-language    attributes-natural-  name
                                 language
  0x0005                                              value-length
  en-us                          en-US                value
  0x45                           uri type             value-tag
  0x000b                                              name-length
  printer-uri                    printer-uri          name
  0x002c                                              value-length
  ipp://printer.example.com/ipp/ printer pinetree     value
  print/pinetree
  0x03                           end-of-attributes    end-of-
                                                      attributes-tag

A.7. Create-Job Request with Collection Attributes

 The following is an example of Create-Job request with the "media-
 col" collection attribute [PWG5100.3] with the value "media-
 size={x-dimension=21000 y-dimension=29700} media-type='stationery'":
 Octets                         Symbolic Value       Protocol field
 0x0101                         1.1                  version-number
 0x0005                         Create-Job           operation-id
 0x00000001                     1                    request-id

Sweet & McDonald Standards Track [Page 46] RFC 8010 IPP/1.1: Encoding and Transport January 2017

 0x01                           start operation-     operation-
                                attributes           attributes-tag
 0x47                           charset type         value-tag
 0x0012                                              name-length
 attributes-charset             attributes-charset   name
 0x0005                                              value-length
 utf-8                          UTF-8                value
 0x48                           natural-language     value-tag
                                type
 0x001b                                              name-length
 attributes-natural-language    attributes-natural-  name
                                language
 0x0005                                              value-length
 en-us                          en-US                value
 0x45                           uri type             value-tag
 0x000b                                              name-length
 printer-uri                    printer-uri          name
 0x002c                                              value-length
 ipp://printer.example.com/ipp/ printer pinetree     value
 print/pinetree
 0x34                           begCollection        value-tag
 0x0009                         9                    name-length
 media-col                      media-col            name
 0x0000                         0                    value-length
 0x4a                           memberAttrName       value-tag
 0x0000                         0                    name-length
 0x000a                         10                   value-length
 media-size                     media-size           value (member-
                                                     name)
 0x34                           begCollection        member-value-tag
 0x0000                         0                    name-length
 0x0000                         0                    member-value-
                                                     length
 0x4a                           memberAttrName       value-tag
 0x0000                         0                    name-length
 0x000b                         11                   value-length
 x-dimension                    x-dimension          value (member-
                                                     name)
 0x21                           integer              member-value-tag
 0x0000                         0                    name-length
 0x0004                         4                    member-value-
                                                     length
 0x00005208                     21000                member-value
 0x4a                           memberAttrName       value-tag
 0x0000                         0                    name-length
 0x000b                         11                   value-length
 y-dimension                    y-dimension          value (member-
                                                     name)

Sweet & McDonald Standards Track [Page 47] RFC 8010 IPP/1.1: Encoding and Transport January 2017

 0x21                           integer              member-value-tag
 0x0000                         0                    name-length
 0x0004                         4                    member-value-
                                                     length
 0x00007404                     29700                member-value
 0x37                           endCollection        end-value-tag
 0x0000                         0                    end-name-length
 0x0000                         0                    end-value-length
 0x4a                           memberAttrName       value-tag
 0x0000                         0                    name-length
 0x000a                         10                   value-length
 media-type                     media-type           value (member-
                                                     name)
 0x44                           keyword              member-value-tag
 0x0000                         0                    name-length
 0x000a                         10                   member-value-
                                                     length
 stationery                     stationery           member-value
 0x37                           endCollection        end-value-tag
 0x0000                         0                    end-name-length
 0x0000                         0                    end-value-length
 0x03                           end-of-attributes    end-of-
                                                     attributes-tag

A.8. Get-Jobs Request

 The following is an example of Get-Jobs request with parameters but
 no attributes:
  Octets                         Symbolic Value       Protocol field
  0x0101                         1.1                  version-number
  0x000a                         Get-Jobs             operation-id
  0x0000007b                     123                  request-id
  0x01                           start operation-     operation-
                                 attributes           attributes-tag
  0x47                           charset type         value-tag
  0x0012                                              name-length
  attributes-charset             attributes-charset   name
  0x0005                                              value-length
  utf-8                          UTF-8                value
  0x48                           natural-language     value-tag
                                 type
  0x001b                                              name-length
  attributes-natural-language    attributes-natural-  name
                                 language
  0x0005                                              value-length
  en-us                          en-US                value

Sweet & McDonald Standards Track [Page 48] RFC 8010 IPP/1.1: Encoding and Transport January 2017

  0x45                           uri type             value-tag
  0x000b                                              name-length
  printer-uri                    printer-uri          name
  0x002c                                              value-length
  ipp://printer.example.com/ipp/ printer pinetree     value
  print/pinetree
  0x21                           integer type         value-tag
  0x0005                                              name-length
  limit                          limit                name
  0x0004                                              value-length
  0x00000032                     50                   value
  0x44                           keyword type         value-tag
  0x0014                                              name-length
  requested-attributes           requested-attributes name
  0x0006                                              value-length
  job-id                         job-id               value
  0x44                           keyword type         value-tag
  0x0000                         additional value     name-length
  0x0008                                              value-length
  job-name                       job-name             value
  0x44                           keyword type         value-tag
  0x0000                         additional value     name-length
  0x000f                                              value-length
  document-format                document-format      value
  0x03                           end-of-attributes    end-of-
                                                      attributes-tag

A.9. Get-Jobs Response

 The following is an example of a Get-Jobs response from a previous
 request with three Jobs.  The Printer returns no information about
 the second Job (because of security reasons):
 Octets                  Symbolic Value          Protocol field
 0x0101                  1.1                     version-number
 0x0000                  successful-ok           status-code
 0x0000007b              123                     request-id (echoed
                                                 back)
 0x01                    start operation-        operation-attributes-
                         attributes              tag
 0x47                    charset type            value-tag
 0x0012                                          name-length
 attributes-charset      attributes-charset      name
 0x0005                                          value-length
 utf-8                   UTF-8                   value
 0x48                    natural-language type   value-tag
 0x001b                                          name-length

Sweet & McDonald Standards Track [Page 49] RFC 8010 IPP/1.1: Encoding and Transport January 2017

 attributes-natural-     attributes-natural-     name
 language                language
 0x0005                                          value-length
 en-us                   en-US                   value
 0x41                    textWithoutLanguage     value-tag
                         type
 0x000e                                          name-length
 status-message          status-message          name
 0x000d                                          value-length
 successful-ok           successful-ok           value
 0x02                    start job-attributes    job-attributes-tag
                         (1st  object)
 0x21                    integer type            value-tag
 0x0006                                          name-length
 job-id                  job-id                  name
 0x0004                                          value-length
 147                     147                     value
 0x36                    nameWithLanguage        value-tag
 0x0008                                          name-length
 job-name                job-name                name
 0x000c                                          value-length
 0x0005                                          sub-value-length
 fr-ca                   fr-CA                   value
 0x0003                                          sub-value-length
 fou                     fou                     name
 0x02                    start job-attributes    job-attributes-tag
                         (2nd object)
 0x02                    start job-attributes    job-attributes-tag
                         (3rd object)
 0x21                    integer type            value-tag
 0x0006                                          name-length
 job-id                  job-id                  name
 0x0004                                          value-length
 148                     149                     value
 0x36                    nameWithLanguage        value-tag
 0x0008                                          name-length
 job-name                job-name                name
 0x0012                                          value-length
 0x0005                                          sub-value-length
 de-CH                   de-CH                   value
 0x0009                                          sub-value-length
 isch guet               isch guet               name
 0x03                    end-of-attributes       end-of-attributes-tag

Sweet & McDonald Standards Track [Page 50] RFC 8010 IPP/1.1: Encoding and Transport January 2017

Acknowledgements

 The authors would like to acknowledge the following individuals for
 their contributions to the original IPP/1.1 specifications:
 Sylvan Butler, Roger deBry, Tom Hastings, Robert Herriot (the
 original editor of RFC 2910), Paul Moore, Kirk Ocke, Randy Turner,
 John Wenn, and Peter Zehler.

Authors' Addresses

 Michael Sweet
 Apple Inc.
 1 Infinite Loop
 MS 111-HOMC
 Cupertino, CA  95014
 United States of America
 Email: msweet@apple.com
 Ira McDonald
 High North, Inc.
 PO Box 221
 Grand Marais, MI  49839
 United States of America
 Phone: +1 906-494-2434
 Email: blueroofmusic@gmail.com

Sweet & McDonald Standards Track [Page 51]

Internet Engineering Task Force (IETF) M. Sweet Request for Comments: 8011 Apple Inc. Obsoletes: 2911, 3381, 3382 I. McDonald Category: Standards Track High North, Inc. ISSN: 2070-1721 January 2017

        Internet Printing Protocol/1.1: Model and Semantics

Abstract

 The Internet Printing Protocol (IPP) is an application-level protocol
 for distributed printing using Internet tools and technologies.  This
 document describes a simplified model consisting of abstract objects,
 attributes, and operations that is independent of encoding and
 transport.  The model consists of several objects, including Printers
 and Jobs.  Jobs optionally support multiple Documents.
 IPP semantics allow End Users and Operators to query Printer
 capabilities; submit Print Jobs; inquire about the status of Print
 Jobs and Printers; and cancel, hold, and release Print Jobs.  IPP
 semantics also allow Operators to pause and resume Jobs and Printers.
 Security, internationalization, and directory issues are also
 addressed by the model and semantics.  The IPP message encoding and
 transport are described in "Internet Printing Protocol/1.1: Encoding
 and Transport" (RFC 8010).
 This document obsoletes RFCs 2911, 3381, and 3382.

Status of This Memo

 This is an Internet Standards Track document.
 This document is a product of the Internet Engineering Task Force
 (IETF).  It represents the consensus of the IETF community.  It has
 received public review and has been approved for publication by the
 Internet Engineering Steering Group (IESG).  Further information on
 Internet Standards is available in Section 2 of RFC 7841.
 Information about the current status of this document, any errata,
 and how to provide feedback on it may be obtained at
 http://www.rfc-editor.org/info/rfc8011.

Sweet & McDonald Standards Track [Page 1] RFC 8011 IPP/1.1: Model and Semantics January 2017

Copyright Notice

 Copyright (c) 2017 IETF Trust and the persons identified as the
 document authors.  All rights reserved.
 This document is subject to BCP 78 and the IETF Trust's Legal
 Provisions Relating to IETF Documents
 (http://trustee.ietf.org/license-info) in effect on the date of
 publication of this document.  Please review these documents
 carefully, as they describe your rights and restrictions with respect
 to this document.  Code Components extracted from this document must
 include Simplified BSD License text as described in Section 4.e of
 the Trust Legal Provisions and are provided without warranty as
 described in the Simplified BSD License.

Sweet & McDonald Standards Track [Page 2] RFC 8011 IPP/1.1: Model and Semantics January 2017

Table of Contents

 1. Introduction ....................................................9
    1.1. Simplified Printing Model .................................12
 2. Conventions Used in This Document ..............................15
    2.1. Requirements Language .....................................15
    2.2. Printing Terminology ......................................15
    2.3. Model Terminology .........................................16
         2.3.1. Administrator ......................................16
         2.3.2. Attributes .........................................16
                2.3.2.1. Attribute Group Name ......................16
                2.3.2.2. Attribute Name ............................16
                2.3.2.3. Attribute Syntax ..........................16
                2.3.2.4. Attribute Value ...........................17
         2.3.3. End User ...........................................17
         2.3.4. Impression .........................................17
         2.3.5. Input Page .........................................17
         2.3.6. Job Creation Operation .............................17
         2.3.7. Keyword ............................................17
         2.3.8. Media Sheet ........................................18
         2.3.9. Operator ...........................................18
         2.3.10. Set ...............................................18
         2.3.11. Support of Attributes .............................18
         2.3.12. Terminating State .................................21
    2.4. Abbreviations .............................................21
 3. IPP Objects ....................................................22
    3.1. Printer Object ............................................22
    3.2. Job Object ................................................25
    3.3. Object Relationships ......................................25
    3.4. Object Identity ...........................................26
 4. IPP Operations .................................................29
    4.1. Common Semantics ..........................................30
         4.1.1. Required Parameters ................................30
         4.1.2. Operation IDs and Request IDs ......................31
         4.1.3. Attributes .........................................31
         4.1.4. Character Set and Natural Language
                Operation Attributes ...............................33
                4.1.4.1. Request Operation Attributes ..............34
                4.1.4.2. Response Operation Attributes .............38
         4.1.5. Operation Targets ..................................39
         4.1.6. Operation Response Status-Code Values and
                Status Messages ....................................41
                4.1.6.1. "status-code" (type2 enum) ................41
                4.1.6.2. "status-message" (text(255)) ..............42
                4.1.6.3. "detailed-status-message" (text(MAX)) .....43
                4.1.6.4. "document-access-error" (text(MAX)) .......43

Sweet & McDonald Standards Track [Page 3] RFC 8011 IPP/1.1: Model and Semantics January 2017

         4.1.7. Unsupported Attributes .............................44
         4.1.8. Versions ...........................................45
         4.1.9. Job Creation Operations ............................48
    4.2. Printer Operations ........................................50
         4.2.1. Print-Job Operation ................................51
                4.2.1.1. Print-Job Request .........................51
                4.2.1.2. Print-Job Response ........................56
         4.2.2. Print-URI Operation ................................58
         4.2.3. Validate-Job Operation .............................59
         4.2.4. Create-Job Operation ...............................59
         4.2.5. Get-Printer-Attributes Operation ...................60
                4.2.5.1. Get-Printer-Attributes Request ............61
                4.2.5.2. Get-Printer-Attributes Response ...........63
         4.2.6. Get-Jobs Operation .................................64
                4.2.6.1. Get-Jobs Request ..........................65
                4.2.6.2. Get-Jobs Response .........................66
         4.2.7. Pause-Printer Operation ............................68
                4.2.7.1. Pause-Printer Request .....................71
                4.2.7.2. Pause-Printer Response ....................71
         4.2.8. Resume-Printer Operation ...........................72
         4.2.9. Purge-Jobs Operation ...............................73
    4.3. Job Operations ............................................73
         4.3.1. Send-Document Operation ............................74
                4.3.1.1. Send-Document Request .....................75
                4.3.1.2. Send-Document Response ....................77
         4.3.2. Send-URI Operation .................................78
         4.3.3. Cancel-Job Operation ...............................78
                4.3.3.1. Cancel-Job Request ........................80
                4.3.3.2. Cancel-Job Response .......................81
         4.3.4. Get-Job-Attributes Operation .......................81
                4.3.4.1. Get-Job-Attributes Request ................82
                4.3.4.2. Get-Job-Attributes Response ...............83
         4.3.5. Hold-Job Operation .................................84
                4.3.5.1. Hold-Job Request ..........................86
                4.3.5.2. Hold-Job Response .........................87
         4.3.6. Release-Job Operation ..............................87
         4.3.7. Restart-Job Operation ..............................89
                4.3.7.1. Restart-Job Request .......................91
                4.3.7.2. Restart-Job Response ......................92
 5. Object Attributes ..............................................92
    5.1. Attribute Syntaxes ........................................92
         5.1.1. Out-of-Band Values - 'unknown',
                'unsupported', and 'no-value' ......................93
         5.1.2. 'text' .............................................93
                5.1.2.1. 'textWithoutLanguage' .....................94
                5.1.2.2. 'textWithLanguage' ........................94

Sweet & McDonald Standards Track [Page 4] RFC 8011 IPP/1.1: Model and Semantics January 2017

         5.1.3. 'name' .............................................95
                5.1.3.1. 'nameWithoutLanguage' .....................96
                5.1.3.2. 'nameWithLanguage' ........................96
                5.1.3.3. Matching 'name' Attribute Values ..........97
         5.1.4. 'keyword' ..........................................98
         5.1.5. 'enum' .............................................99
         5.1.6. 'uri' .............................................100
         5.1.7. 'uriScheme' .......................................100
         5.1.8. 'charset' .........................................101
         5.1.9. 'naturalLanguage' .................................102
         5.1.10. 'mimeMediaType' ..................................102
                5.1.10.1. 'application/octet-stream' -
                          Auto-Sensing the Document Format ........103
         5.1.11. 'octetString' ....................................104
         5.1.12. 'boolean' ........................................104
         5.1.13. 'integer' ........................................104
         5.1.14. 'rangeOfInteger' .................................105
         5.1.15. 'dateTime' .......................................105
         5.1.16. 'resolution' .....................................105
         5.1.17. 'collection' .....................................105
         5.1.18. '1setOf X' .......................................106
    5.2. Job Template Attributes ..................................106
         5.2.1. job-priority (integer(1:100)) .....................109
         5.2.2. job-hold-until (type2 keyword | name(MAX)) ........111
         5.2.3. job-sheets (type2 keyword | name(MAX)) ............112
         5.2.4. multiple-document-handling (type2 keyword) ........113
         5.2.5. copies (integer(1:MAX)) ...........................115
         5.2.6. finishings (1setOf type2 enum) ....................115
         5.2.7. page-ranges (1setOf rangeOfInteger(1:MAX)) ........118
         5.2.8. sides (type2 keyword) .............................119
         5.2.9. number-up (integer(1:MAX)) ........................120
         5.2.10. orientation-requested (type2 enum) ...............120
         5.2.11. media (type2 keyword | name(MAX)) ................123
         5.2.12. printer-resolution (resolution) ..................124
         5.2.13. print-quality (type2 enum) .......................124
    5.3. Job Description and Status Attributes ....................124
         5.3.1. job-id (integer(1:MAX)) ...........................126
         5.3.2. job-uri (uri) .....................................126
         5.3.3. job-printer-uri (uri) .............................127
         5.3.4. job-more-info (uri) ...............................127
         5.3.5. job-name (name(MAX)) ..............................127
         5.3.6. job-originating-user-name (name(MAX)) .............128
         5.3.7. job-state (type1 enum) ............................128
                5.3.7.1. Forwarding Servers .......................132
                5.3.7.2. Partitioning of Job States ...............132
         5.3.8. job-state-reasons (1setOf type2 keyword) ..........133
         5.3.9. job-state-message (text(MAX)) .....................138
         5.3.10. job-detailed-status-messages (1setOf text(MAX)) ..139

Sweet & McDonald Standards Track [Page 5] RFC 8011 IPP/1.1: Model and Semantics January 2017

         5.3.11. job-document-access-errors (1setOf text(MAX)) ....139
         5.3.12. number-of-documents (integer(0:MAX)) .............139
         5.3.13. output-device-assigned (name(127)) ...............139
         5.3.14. Event Time Job Status Attributes .................140
                5.3.14.1. time-at-creation (integer(MIN:MAX)) .....140
                5.3.14.2. time-at-processing (integer(MIN:MAX)) ...141
                5.3.14.3. time-at-completed (integer(MIN:MAX)) ....141
                5.3.14.4. job-printer-up-time (integer(1:MAX)) ....141
                5.3.14.5. date-time-at-creation
                          (dateTime|unknown) ......................141
                5.3.14.6. date-time-at-processing
                          (dateTime|unknown|no-value) .............141
                5.3.14.7. date-time-at-completed
                          (dateTime|unknown|no-value) .............141
         5.3.15. number-of-intervening-jobs (integer(0:MAX)) ......142
         5.3.16. job-message-from-operator (text(127)) ............142
         5.3.17. Job Size Attributes ..............................142
                5.3.17.1. job-k-octets (integer(0:MAX)) ...........142
                5.3.17.2. job-impressions (integer(0:MAX)) ........143
                5.3.17.3. job-media-sheets (integer(1:MAX)) .......143
         5.3.18. Job Progress Attributes ..........................144
                5.3.18.1. job-k-octets-processed
                          (integer(0:MAX)) ........................144
                5.3.18.2. job-impressions-completed
                          (integer(0:MAX)) ........................144
                5.3.18.3. job-media-sheets-completed
                          (integer(0:MAX)) ........................144
         5.3.19. attributes-charset (charset) .....................144
         5.3.20. attributes-natural-language (naturalLanguage) ....145
    5.4. Printer Description and Status Attributes ................145
         5.4.1. printer-uri-supported (1setOf uri) ................147
         5.4.2. uri-authentication-supported (1setOf type2
                keyword) ..........................................148
         5.4.3. uri-security-supported (1setOf type2 keyword) .....149
         5.4.4. printer-name (name(127)) ..........................150
         5.4.5. printer-location (text(127)) ......................150
         5.4.6. printer-info (text(127)) ..........................151
         5.4.7. printer-more-info (uri) ...........................151
         5.4.8. printer-driver-installer (uri) ....................151
         5.4.9. printer-make-and-model (text(127)) ................151
         5.4.10. printer-more-info-manufacturer (uri) .............151
         5.4.11. printer-state (type1 enum) .......................152
         5.4.12. printer-state-reasons (1setOf type2 keyword) .....152
         5.4.13. printer-state-message (text(MAX)) ................157
         5.4.14. ipp-versions-supported (1setOf type2 keyword) ....157
         5.4.15. operations-supported (1setOf type2 enum) .........157

Sweet & McDonald Standards Track [Page 6] RFC 8011 IPP/1.1: Model and Semantics January 2017

         5.4.16. multiple-document-jobs-supported (boolean) .......159
         5.4.17. charset-configured (charset) .....................159
         5.4.18. charset-supported (1setOf charset) ...............159
         5.4.19. natural-language-configured (naturalLanguage) ....160
         5.4.20. generated-natural-language-supported
                 (1setOf naturalLanguage) .........................160
         5.4.21. document-format-default (mimeMediaType) ..........160
         5.4.22. document-format-supported (1setOf
                 mimeMediaType) ...................................161
         5.4.23. printer-is-accepting-jobs (boolean) ..............161
         5.4.24. queued-job-count (integer(0:MAX)) ................161
         5.4.25. printer-message-from-operator (text(127)) ........161
         5.4.26. color-supported (boolean) ........................161
         5.4.27. reference-uri-schemes-supported (1setOf
                 uriScheme) .......................................162
         5.4.28. pdl-override-supported (type2 keyword) ...........162
         5.4.29. printer-up-time (integer(1:MAX)) .................162
         5.4.30. printer-current-time (dateTime|unknown) ..........163
         5.4.31. multiple-operation-time-out (integer(1:MAX)) .....164
         5.4.32. compression-supported (1setOf type2 keyword) .....164
         5.4.33. job-k-octets-supported (rangeOfInteger(0:MAX)) ...165
         5.4.34. job-impressions-supported
                 (rangeOfInteger(0:MAX)) ..........................165
         5.4.35. job-media-sheets-supported
                 (rangeOfInteger(1:MAX)) ..........................165
         5.4.36. pages-per-minute (integer(0:MAX)) ................165
         5.4.37. pages-per-minute-color (integer(0:MAX)) ..........165
 6. Conformance ...................................................166
    6.1. Client Conformance Requirements ..........................166
    6.2. IPP Object Conformance Requirements ......................168
         6.2.1. Objects ...........................................168
         6.2.2. Operations ........................................168
         6.2.3. IPP Object Attributes .............................170
         6.2.4. Versions ..........................................170
         6.2.5. Extensions ........................................171
         6.2.6. Attribute Syntaxes ................................171
         6.2.7. Security ..........................................172
    6.3. Charset and Natural Language Requirements ................172
 7. IANA Considerations ...........................................173
    7.1. Object Extensions ........................................174
    7.2. Attribute Extensibility ..................................174
    7.3. Keyword Extensibility ....................................175
    7.4. Enum Extensibility .......................................176
    7.5. Attribute Group Extensibility ............................176
    7.6. Out-of-Band Attribute Value Extensibility ................176
    7.7. Attribute Syntax Extensibility ...........................177
    7.8. Operation Extensibility ..................................177
    7.9. Status-Code Extensibility ................................178

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 8. Internationalization Considerations ...........................179
 9. Security Considerations .......................................183
    9.1. Security Scenarios .......................................184
         9.1.1. Client and Server in the Same Security Domain .....184
         9.1.2. Client and Server in Different Security Domains ...184
         9.1.3. Print by Reference ................................184
    9.2. URIs in Operation, Job, and Printer Attributes ...........185
    9.3. URIs for Each Authentication Mechanism ...................185
    9.4. Restricted Queries .......................................186
    9.5. Operations Performed by Operators and Administrators .....186
    9.6. Queries on Jobs Submitted Using Non-IPP Protocols ........186
 10. Changes since RFC 2911 .......................................187
 11. References ...................................................188
    11.1. Normative References ....................................188
    11.2. Informative References ..................................194
 Appendix A. Formats for IPP Registration Proposals ...............197
   A.1. Attribute Registration ....................................197
   A.2. type2 'keyword' Attribute Value Registration ..............198
   A.3. type2 'enum' Attribute Value Registration .................198
   A.4. Operation Registration ....................................199
   A.5. Status-Code Registration ..................................199
 Appendix B. Status-Code Values and Suggested Status-Code
             Messages .............................................200
   B.1. Status-Code Values ........................................201
     B.1.1. Informational .........................................201
     B.1.2. Successful Status-Code Values .........................201
       B.1.2.1. successful-ok (0x0000) ............................201
       B.1.2.2. successful-ok-ignored-or-substituted-attributes
                (0x0001) ..........................................202
       B.1.2.3. successful-ok-conflicting-attributes (0x0002) .....202
     B.1.3. Redirection Status-Code Values ........................202
     B.1.4. Client Error Status-Code Values .......................202
       B.1.4.1. client-error-bad-request (0x0400) .................203
       B.1.4.2. client-error-forbidden (0x0401) ...................203
       B.1.4.3. client-error-not-authenticated (0x0402) ...........203
       B.1.4.4. client-error-not-authorized (0x0403) ..............203
       B.1.4.5. client-error-not-possible (0x0404) ................203
       B.1.4.6. client-error-timeout (0x0405) .....................204
       B.1.4.7. client-error-not-found (0x0406) ...................204
       B.1.4.8. client-error-gone (0x0407) ........................204
       B.1.4.9. client-error-request-entity-too-large (0x0408) ....205
       B.1.4.10. client-error-request-value-too-long (0x0409) .....205
       B.1.4.11. client-error-document-format-not-supported
                 (0x040a) .........................................205
       B.1.4.12. client-error-attributes-or-values-not-supported
                 (0x040b) .........................................206
       B.1.4.13. client-error-uri-scheme-not-supported (0x040c) ...206
       B.1.4.14. client-error-charset-not-supported (0x040d) ......206

Sweet & McDonald Standards Track [Page 8] RFC 8011 IPP/1.1: Model and Semantics January 2017

       B.1.4.15. client-error-conflicting-attributes (0x040e) .....207
       B.1.4.16. client-error-compression-not-supported (0x040f) ..207
       B.1.4.17. client-error-compression-error (0x0410) ..........207
       B.1.4.18. client-error-document-format-error (0x0411) ......207
       B.1.4.19. client-error-document-access-error (0x0412) ......207
     B.1.5. Server Error Status-Code Values .......................208
       B.1.5.1. server-error-internal-error (0x0500) ..............208
       B.1.5.2. server-error-operation-not-supported (0x0501) .....208
       B.1.5.3. server-error-service-unavailable (0x0502) .........208
       B.1.5.4. server-error-version-not-supported (0x0503) .......209
       B.1.5.5. server-error-device-error (0x0504) ................209
       B.1.5.6. server-error-temporary-error (0x0505) .............210
       B.1.5.7. server-error-not-accepting-jobs (0x0506) ..........210
       B.1.5.8. server-error-busy (0x0507) ........................210
       B.1.5.9. server-error-job-canceled (0x0508) ................210
       B.1.5.10. server-error-multiple-document-jobs-not-supported
                 (0x0509) .........................................210
   B.2. Status-Code Values for IPP Operations .....................211
 Appendix C. Processing IPP Attributes ............................213
   C.1. Fidelity ..................................................213
   C.2. Page Description Language (PDL) Override ..................215
   C.3. Using Job Template Attributes during Document Processing ..217
 Appendix D. Generic Directory Schema .............................218
 Acknowledgements .................................................221
 Authors' Addresses ...............................................221

1. Introduction

 The Internet Printing Protocol (IPP) is an application-level protocol
 for distributed printing using Internet tools and technologies.  IPP
 version 1.1 (IPP/1.1) focuses primarily on End User functionality
 with a few administrative operations included.  IPP versions 2.0,
 2.1, and 2.2 provide many new operations and are defined separately.
 This document is just one of a suite of documents that fully define
 IPP.  The full set of IETF IPP documents includes:
    Design Goals for an Internet Printing Protocol [RFC2567]
    Rationale for the Structure of the Model and Protocol for the
    Internet Printing Protocol [RFC2568]
    Internet Printing Protocol/1.1: Model and Semantics (this
    document)
    Internet Printing Protocol/1.1: Encoding and Transport [RFC8010]
    Internet Printing Protocol/1.1: Implementor's Guide [RFC3196]

Sweet & McDonald Standards Track [Page 9] RFC 8011 IPP/1.1: Model and Semantics January 2017

    Internet Printing Protocol/1.1: IPP URL Scheme [RFC3510]
    Internet Printing Protocol (IPP) over HTTPS Transport Binding and
    the 'ipps' URI Scheme [RFC7472]
    Internet Printing Protocol (IPP): Requirements for Job, Printer,
    and Device Administrative Operations [RFC3239]
    Internet Printing Protocol (IPP): Job and Printer Set Operations
    [RFC3380]
    Internet Printing Protocol (IPP): Job and Printer Administrative
    Operations [RFC3998]
    Internet Printing Protocol (IPP): Requirements for IPP
    Notifications [RFC3997]
    Internet Printing Protocol (IPP): Event Notifications and
    Subscriptions [RFC3995]
    Internet Printing Protocol (IPP): The 'ippget' Delivery Method for
    Event Notifications [RFC3996]
    Mapping between LPD and IPP Protocols [RFC2569]
 Anyone reading these documents for the first time is strongly
 encouraged to read the IPP documents in the above order.  Additional
 IPP specifications have been published by the IEEE-ISTO Printer
 Working Group's IPP Workgroup [PWG-IPP-WG].  The following standards
 are highly recommended reading:
    PWG Media Standardized Names 2.0 (MSN2) [PWG5101.1]
    IPP Finishings 2.0 (FIN) [PWG5100.1]
    Internet Printing Protocol (IPP): "output-bin" attribute extension
    [PWG5100.2]
    Internet Printing Protocol (IPP): Production Printing Attributes -
    Set 1 [PWG5100.3] (for "media-col" Job Template attribute)
    Standard for The Internet Printing Protocol (IPP): Document Object
    [PWG5100.5]
    Standard for The Internet Printing Protocol (IPP): Page Overrides
    [PWG5100.6]

Sweet & McDonald Standards Track [Page 10] RFC 8011 IPP/1.1: Model and Semantics January 2017

    Standard for The Internet Printing Protocol (IPP): Job Extensions
    [PWG5100.7]
    Standard for Internet Printing Protocol (IPP): "-actual"
    attributes [PWG5100.8]
    Internet Printing Protocol (IPP): Printer State Extensions v1.0
    [PWG5100.9]
    Internet Printing Protocol (IPP): Job and Printer Extensions -
    Set 2 (JPS2) [PWG5100.11]
    IPP Version 2.0, 2.1, and 2.2 [PWG5100.12]
    IPP: Job and Printer Extensions - Set 3 (JPS3) [PWG5100.13]
    IPP Everywhere [PWG5100.14]
    IPP FaxOut Service [PWG5100.15]
    IPP Transaction-Based Printing Extensions [PWG5100.16]
    IPP Scan Service (SCAN) [PWG5100.17]
    IPP Shared Infrastructure Extensions (INFRA) [PWG5100.18]
    IPP Implementor's Guide v2.0 (IG) [PWG5100.19]
 This document is organized as follows:
 o  The rest of Section 1 is an introduction to the IPP simplified
    model for distributed printing;
 o  Section 2 defines the terminology and conventions used within this
    document;
 o  Section 3 introduces the object types covered in this document
    with their basic behaviors, attributes, and interactions;
 o  Section 4 defines the core operations for IPP/1.1.  IPP operations
    are synchronous -- each operation has both a request and a
    response;
 o  Section 5 defines the core attributes (and their syntaxes) that
    are used in the model;

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 o  Sections 6 and 7 summarize the implementation conformance
    requirements for objects that support the protocol and IANA
    considerations, respectively;
 o  Sections 8 and 9 cover the internationalization and security
    considerations for IPP; and
 o  The appendices provide a reference for status-code values,
    processing of IPP attributes, and the generic directory schema.

1.1. Simplified Printing Model

 In order to achieve its goal of realizing a workable printing
 protocol for the Internet, the Internet Printing Protocol (IPP) is
 based on a simplified printing model that abstracts the many
 components of real-world printing solutions.  The Internet is a
 distributed computing environment where requesters of print services
 (Clients, applications, Printer drivers, etc.) cooperate and interact
 with print service providers.  This document (sometimes referred to
 here as the "Model and Semantics" document) describes a simple,
 abstract model for IPP even though the underlying configurations can
 be complex "n-tier" client/server systems.  An important simplifying
 step in the IPP Model is to expose only the key objects and
 interfaces required for printing.  The model described in this
 document does not include features, interfaces, and relationships
 that are beyond the scope of IPP/1.1.  IPP/1.1 incorporates many of
 the relevant ideas and lessons learned from other specification and
 development efforts [HTPP] [ISO10175] [LDPA] [P1387.4] [PSIS]
 [RFC1179] [SWP].  IPP is heavily influenced by the printing model
 introduced in the Document Printing Application (DPA) [ISO10175]
 standard.  Although DPA specifies both End User and administrative
 features, IPP/1.1 focuses primarily on End User functionality with a
 few additional OPTIONAL operations for Administrators and Operators.
 The IPP Model encapsulates the important components of distributed
 printing into the following IPP object types:
 o  Printer (Section 3.1)
 o  Job (Section 3.2)
 o  Document (see [PWG5100.5])
 o  Subscription (see [RFC3995])
 Each object type has an associated set of operations (see Section 4)
 and attributes (see Section 5).

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 It is important, however, to understand that in real system
 implementations (which lie underneath the abstracted IPP Model),
 there are other components of a print service that are not explicitly
 defined in the IPP Model.  The following figure illustrates where IPP
 fits with respect to these other components.
                              +----------------+
                              |   Application  |
                    o         + . . . . . . .  |
                   \|/        |    Spooler     |
                   / \        + . . . . . . .  |   +---------+
                 End User     | Printer Driver |---|  File   |
       +-----------+ +-----+  +-------+--------+   +----+----+
       |  Browser  | | GUI |          |                 |
       +-----+-----+ +--+--+          |                 |
             |          |             |                 |
             |      +---+-------------+--+              |
 N   D   S   |      |      IPP Client    |--------------+
 O   I   E   |      +---------+----------+
 T   R   C   |                |
 I   E   U   |
 F   C   R   -------------- Transport -------------------
 I   T   I
 C   O   T                    |         --+
 A   R   Y           +--------+--------+  |
 T   Y               |    IPP Server   |  |
 I                   +--------+--------+  |
 O                            |           |
 N                   +-----------------+  | IPP Printer
                     |  Print Service  |  |
                     +-----------------+  |
                              |         --+
                     +-----------------+
                     | Output Device(s)|
                     +-----------------+
                          Figure 1: IPP Model
 An IPP Printer object ("Printer") encapsulates the functions normally
 associated with physical Output Devices along with the spooling,
 scheduling, and multiple device management functions often associated
 with a print server.  Printers are optionally registered as entries
 in a directory where End Users find and select them based on some
 sort of filtered context-based searching mechanism (see Appendix D).
 The directory is used to store relatively static information about
 the Printer, allowing End Users to search for and find Printers that
 match their search criteria -- for example, name, location, context,
 Printer capabilities, etc.  The more dynamic information, such as

Sweet & McDonald Standards Track [Page 13] RFC 8011 IPP/1.1: Model and Semantics January 2017

 state, currently loaded and ready media, number of Jobs at the
 Printer, errors, warnings, and so forth, is directly associated with
 the Printer itself rather than with the entry in the directory, which
 only references the Printer.
 IPP Clients ("Clients") implement IPP on the Client side and give
 End Users (or programs running on behalf of End Users) the ability to
 query Printers and submit and manage Print Jobs.  An IPP server is
 just that part of the Printer object that implements the server-side
 protocol.  The rest of the Printer object implements (or gateways
 into) the application semantics of the print service itself.
 Printers can be embedded in an Output Device or can be implemented on
 a host on the network that communicates with an Output Device.
 When a Job is submitted to the Printer and the Printer has validated
 the attributes in the submission request, the Printer creates a new
 IPP Job object ("Job").  The End User then interacts with this new
 Job to query its status and monitor the progress of the Job.  An
 End User can also cancel their Print Jobs by using the Job's
 Cancel-Job operation.  An End User can also hold, release, and
 restart their Print Jobs using the Job's OPTIONAL Hold-Job,
 Release-Job, and Restart-Job operations, if implemented.
 A privileged Operator or Administrator of a Printer can cancel, hold,
 release, and restart any user's Job using the REQUIRED Cancel-Job and
 the OPTIONAL Hold-Job, Release-Job, and Restart-Job operations.  In
 addition, a privileged Operator or Administrator of a Printer can
 pause, resume, or purge (Jobs from) a Printer using the OPTIONAL
 Pause-Printer, Resume-Printer, and Purge-Jobs operations, if
 implemented.
 The notification service is defined in "Internet Printing Protocol
 (IPP): Event Notifications and Subscriptions" [RFC3995].  By using
 such a notification service, the End User is able to register for and
 receive Printer-specific and Job-specific events asynchronously.
 Otherwise, an End User can query the status of Printers and can
 follow the progress of Jobs by polling using the
 Get-Printer-Attributes, Get-Jobs, and Get-Job-Attributes operations.

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2. Conventions Used in This Document

2.1. Requirements Language

 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
 document are to be interpreted as described in [RFC2119].
 The key word "DEPRECATED" in this document refers to an operation,
 attribute, or value that SHOULD NOT be used or supported in new
 implementations.

2.2. Printing Terminology

 Client: Initiator of outgoing IPP session requests and sender of
 outgoing IPP operation requests (Hypertext Transfer Protocol
 (HTTP/1.1) user agent, as defined in [RFC7230]).
 Document: An object created and managed by a Printer that contains
 description, processing, and status information.  A Document object
 can have attached data and is bound to a single Job [PWG5100.5].
 'ipp' URI: An IPP URI as defined in [RFC3510].
 'ipps' URI: An IPP URI as defined in [RFC7472].
 Job: An object created and managed by a Printer that contains
 description, processing, and status information.  The Job also
 contains zero or more Document objects.
 Logical Device: A print server, software service, or gateway that
 processes Jobs and either forwards or stores the processed Job or
 uses one or more Physical Devices to render output.
 Output Device: A single Logical or Physical Device.
 Physical Device: A hardware implementation of an endpoint device,
 e.g., a marking engine, a fax modem, etc.
 Printer: Listener for incoming IPP session requests and receiver of
 incoming IPP operation requests (HTTP/1.1 server, as defined in
 [RFC7230]) that represents one or more Physical Devices or a Logical
 Device.

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2.3. Model Terminology

2.3.1. Administrator

 An End User who is also authorized to manage all aspects of an Output
 Device or Printer, including creating the Printer instances and
 controlling the authorization of other End Users and Operators
 [RFC2567].

2.3.2. Attributes

 An attribute is an item of information that is associated with an
 instance of an IPP object (Printer, Job, etc.).  An attribute
 consists of an attribute name and one or more attribute values.  Each
 attribute has a specific attribute syntax.  All object attributes are
 defined in Section 5, and all operation attributes are defined in
 Section 4.
 Job Template attributes are described in Section 5.2.  The Client
 optionally supplies Job Template attributes in a Job Creation request
 (operation requests that create Job objects).  The Printer object has
 associated attributes that define supported and default values for
 the Printer.

2.3.2.1. Attribute Group Name

 Related attributes are grouped into named groups.  The name of the
 group is a keyword.  The group name can be used in place of naming
 all the attributes in the group explicitly.  Attribute groups are
 defined in Section 4.

2.3.2.2. Attribute Name

 Each attribute is uniquely identified in this document by its
 attribute name.  An attribute name is a keyword.  The keyword
 attribute name is given in the section title in this document that
 describes that attribute.  In running text in this document,
 attribute names are indicated inside double quotation marks (") where
 the quotation marks are not part of the keyword itself.

2.3.2.3. Attribute Syntax

 Each attribute is defined using an explicit syntax type.  In this
 document, each syntax type is defined as a keyword with specific
 meaning.  The "Encoding and Transport" document [RFC8010] indicates
 the actual "on-the-wire" encoding rules for each syntax type.
 Attribute syntax types are defined in Section 5.1.

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2.3.2.4. Attribute Value

 Each attribute has one or more values.  Attribute values are
 represented in the syntax type specified for that attribute.  In
 running text in this document, attribute values are indicated inside
 single quotation marks ('), whether their attribute syntax is
 keyword, integer, text, etc. where the quotation marks are not part
 of the value itself.

2.3.3. End User

 An End User is a person or software process that is authorized to
 perform basic printing functions, including finding/locating a
 Printer, creating a local instance of a Printer, viewing Printer
 status, viewing Printer capabilities, submitting a Print Job, viewing
 Print Job status, and altering the attributes of a Print Job
 [RFC2567].

2.3.4. Impression

 An Impression is the content imposed upon one side of a Media Sheet
 by a marking engine, independent of the number of times that the
 sheet side passes any marker.  An Impression contains one or more
 Input Pages that are imposed (scaled, translated, and/or rotated)
 during processing of the Document data.

2.3.5. Input Page

 An Input Page is a page according to the definition of "pages" in the
 language used to express the Document data.

2.3.6. Job Creation Operation

 A Job Creation operation is any operation that causes the creation of
 a Job object, e.g., the Create-Job, Print-Job, and Print-URI
 operations defined in this document.

2.3.7. Keyword

 Keywords are used within this document as identifiers of semantic
 entities within the abstract model (see Section 5.1.4).  Attribute
 names, some attribute values, attribute syntaxes, and attribute group
 names are represented as keywords.

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2.3.8. Media Sheet

 A Media Sheet is a single instance of a medium, whether printing on
 one or both sides of the medium.  Media Sheets also include sections
 of roll media.

2.3.9. Operator

 An Operator is an End User that also has special rights on the Output
 Device or Printer.  The Operator typically monitors the status of the
 Printer and also manages and controls the Jobs at the Output Device
 [RFC2567].  The Operator is allowed to query and control the Printer,
 Jobs, and Documents based on site policy.

2.3.10. Set

 A Set is a logical boundary between the delivered Media Sheets of a
 printed Job.  For example, in the case of a ten-page single Document
 with collated pages and a request for 50 copies, each of the 50
 printed copies of the Document constitutes a Set.  If the pages were
 uncollated, then 50 copies of each of the individual pages within the
 Document would represent each Set.  Finishing processes operate on
 Sets.

2.3.11. Support of Attributes

 By definition, a Printer supports an attribute only if that Printer
 accepts it in a request or responds with the corresponding attribute
 populated with some value(s) in a response to a query for that
 attribute.  A Printer supports an attribute value if the value is one
 of the Printer's "supported values" attributes.  The device behind a
 Printer can exhibit a behavior that corresponds to some IPP
 attribute, but if the Printer, when queried for that attribute,
 doesn't respond with the attribute, then as far as IPP is concerned,
 that implementation does not support that feature.  If the Printer's
 "xxx-supported" attribute is not populated with a particular value
 (even if that value is a legal value for that attribute), then that
 Printer does not support that particular value.
 A conforming implementation supports all REQUIRED attributes.
 However, even for REQUIRED attributes, conformance to IPP does not
 mandate that all implementations support all possible values
 representing all possible Job processing behaviors and features.  For
 example, if a given instance of a Printer supports only certain
 Document formats, then that Printer responds with the
 "document-format-supported" attribute populated with a set of values,
 or possibly only one value, taken from the entire set of possible
 values defined for that attribute.  This limited set of values

Sweet & McDonald Standards Track [Page 18] RFC 8011 IPP/1.1: Model and Semantics January 2017

 represents the Printer's set of supported Document formats.
 Supporting an attribute and some set of values for that attribute
 enables IPP End Users to be aware of and make use of those features
 associated with that attribute and those values.  If an
 implementation chooses to not support an attribute or some specific
 value, then IPP End Users would have no ability to make use of that
 feature within the context of IPP itself.  However, due to existing
 practice and legacy systems that are not IPP aware, there might be
 some other mechanism outside the scope of IPP to control or request
 the "unsupported" feature (such as embedded instructions within the
 Document data itself).
 For example, consider the following for the "finishings-supported"
 attribute.
 1)  If a Printer is not physically capable of stapling, the
     "finishings-supported" attribute MUST NOT be populated with the
     value of 'staple'.
 2)  A Printer is physically capable of stapling; however, an
     implementation chooses not to support stapling in the IPP
     "finishings" attribute.  In this case, 'staple' MUST NOT be a
     value in the "finishings-supported" Printer Description
     attribute.  Without support for the value 'staple', an IPP
     End User would have no means within the protocol itself to
     request that a Job be stapled.  However, an existing Document
     data formatter might be able to request that the Document be
     stapled directly with an embedded instruction within the Document
     data.  In this case, the IPP implementation does not "support"
     stapling; however, the End User is still able to have some
     control over the stapling of the completed Job.
 3)  A Printer is physically capable of stapling, and an
     implementation chooses to support stapling in the IPP
     "finishings" attribute.  In this case, 'staple' MUST be a value
     in the "finishings-supported" Printer attribute.  Doing so
     enables End Users to be aware of and make use of the stapling
     feature using IPP attributes.
 Even though support for Job Template attributes by a Printer is
 OPTIONAL in IPP/1.1, Printers whose associated device(s) is capable
 of realizing any feature or function that corresponds to an IPP
 attribute and some associated value SHOULD support that IPP attribute
 and value.

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 The set of values in any of the supported value attributes is set
 (populated) by some administrative process or automatic sensing
 mechanism that is outside the scope of this document.  For
 administrative policy and control reasons, an Administrator can
 choose to make only a subset of possible values visible to the
 End User.  In this case, the real Output Device behind the IPP
 Printer abstraction can be capable of a certain feature; however, an
 Administrator is specifying that access to that feature not be
 exposed to the End User through IPP.  Also, since a Printer can
 represent a logical print device (not just a Physical Device), the
 actual process for supporting a value is undefined and left up to the
 implementation.  However, if a Printer supports a value, some manual
 human action might be needed to realize the semantic action
 associated with the value, but no End User action is required.
 For example, if one of the values in the "finishings-supported"
 attribute is 'staple', the actual process might be an automatic
 staple action by a Physical Device controlled by some command sent to
 the device.  Or, the actual process of stapling might be a manual
 action by an Operator at an Operator-attended Printer.
 For another example of how supported attributes function, consider an
 Administrator who desires to control all Print Jobs so that no Job
 sheets are printed in order to conserve paper.  To force no Job
 sheets, the Administrator sets the only supported value for the
 "job-sheets-supported" attribute to 'none'.  In this case, if a
 Client requests anything except 'none', the Job Creation request is
 rejected or the "job-sheets" value is ignored (depending on the value
 of "ipp-attribute-fidelity").  To force the use of Job start/end
 sheets on all Jobs, the Administrator does not include the value
 'none' in the "job-sheets-supported" attribute.  In this case, if a
 Client requests 'none', the Job Creation request is rejected or the
 "job-sheets" value is ignored (again depending on the value of
 "ipp-attribute-fidelity").
 Job Template attributes will typically have corresponding
 "xxx-supported" and "xxx-default" Printer Description attributes that
 contain the supported and default values for the attribute.  For
 capabilities that are not associated with a Job, the convention is to
 have an "xxx-supported" Printer Description attribute that lists the
 supported values and an "xxx-configured" Printer Description
 attribute that contains the value being used by the Printer.  For
 example, the "charset-supported" Printer Description attribute
 (Section 5.4.18) lists the supported character sets for the Printer
 while the "charset-configured" Printer Description attribute
 (Section 5.4.17) specifies the character set being used by the
 Printer.

Sweet & McDonald Standards Track [Page 20] RFC 8011 IPP/1.1: Model and Semantics January 2017

2.3.12. Terminating State

 The final state for a Job or other object is called its Terminating
 State.  For example, the 'aborted', 'canceled', and 'completed' Job
 states are Terminating States.

2.4. Abbreviations

 ABNF: Augmented Backus-Naur Form [RFC5234]
 ASCII: American Standard Code for Information Interchange [RFC20]
 HTTP: Hypertext Transfer Protocol [RFC7230]
 HTTPS: HTTP over TLS [RFC2818]
 IANA: Internet Assigned Numbers Authority
 IEEE: Institute of Electrical and Electronics Engineers
 IESG: Internet Engineering Steering Group
 IPP: Internet Printing Protocol (this document, [RFC8010], and
 [PWG5100.12])
 ISTO: IEEE Industry Standards and Technology Organization
 LPD: Line Printer Daemon Protocol [RFC1179]
 PWG: IEEE-ISTO Printer Working Group
 RFC: Request for Comments
 TCP: Transmission Control Protocol [RFC793]
 TLS: Transport Layer Security [RFC5246]
 URI: Uniform Resource Identifier [RFC3986]
 URL: Uniform Resource Locator [RFC3986]
 UTF-8: Unicode Transformation Format - 8-bit [RFC3629]

Sweet & McDonald Standards Track [Page 21] RFC 8011 IPP/1.1: Model and Semantics January 2017

3. IPP Objects

 This document defines IPP objects of types Printer and Job.  Each
 type of object models relevant aspects of a real-world entity such as
 a real Printer or real Print Job.  Each object type is defined as a
 set of possible attributes that can be supported by instances of that
 object type.  For each object (instance), the actual set of supported
 attributes and values describe a specific implementation.  The
 object's attributes and values describe its state, capabilities,
 realizable features, Job processing functions, and default behaviors
 and characteristics.  For example, the Printer object type is defined
 as a set of attributes that each Printer object potentially supports.
 In the same manner, the Job object type is defined as a set of
 attributes that are potentially supported by each Job object.
 Each attribute included in the set of attributes defining an object
 type is labeled as:
 o  "REQUIRED": each object MUST support the attribute.
 o  "RECOMMENDED": each object SHOULD support the attribute.
 o  "OPTIONAL": each object MAY support the attribute.
 Some definitions of attribute values indicate that an object MUST or
 SHOULD support the value; otherwise, support of the value is
 OPTIONAL.  However, if an implementation supports an attribute, it
 MUST support at least one of the possible values for that attribute.

3.1. Printer Object

 The major component of the IPP Model is the Printer object.  A
 Printer object implements the server side of the IPP/1.1 protocol.
 Using the protocol, End Users can query the attributes of the Printer
 object and submit Print Jobs to the Printer object.  The actual
 implementation components behind the Printer abstraction can take on
 different forms and different configurations.  However, the model
 abstraction allows the details of the configuration of real
 components to remain opaque to the End User.  Section 4 describes
 each of the Printer operations in detail.

Sweet & McDonald Standards Track [Page 22] RFC 8011 IPP/1.1: Model and Semantics January 2017

 The capabilities and state of a Printer object are described by its
 attributes.  Printer attributes are divided into two groups:
 o  "job-template" attributes: These attributes describe supported Job
    processing capabilities and defaults for the Printer object (see
    Section 5.2)
 o  "printer-description" attributes: These attributes describe the
    Printer's identification, state, location, references to other
    sources of information about the Printer object, etc. (see
    Section 5.4)
 Since a Printer object is an abstraction of a generic Document Output
 Device and print service provider, a Printer object could be used to
 represent any real or virtual device with semantics consistent with
 the Printer object, such as a fax device, an imager, or even a CD
 writer.
 Some examples of configurations supporting a Printer object include:
 1.  An Output Device with no spooling capabilities
 2.  An Output Device with a built-in spooler
 3.  A print server supporting IPP with one or more associated Output
     Devices
     3a.  The associated Output Devices are or are not capable of
          spooling Jobs
     3b.  The associated Output Devices possibly support IPP
 Figure 2 shows some examples of how Printers can be realized on top
 of various distributed printing configurations.  The embedded case
 below represents configurations 1 and 2 above.  The "hosted Printer"
 and "fan out" items represent configurations 3a and 3b, respectively.
 In this document, the term "Client" refers to a software entity that
 sends IPP operation requests to an IPP Printer and accepts IPP
 operation responses.  A Client MAY be:
 1.  contained within software controlled by an End User, e.g.,
     activated by the "Print" menu item in an application, or
 2.  the print server component that sends IPP requests to either an
     Output Device or another "downstream" print server.

Sweet & McDonald Standards Track [Page 23] RFC 8011 IPP/1.1: Model and Semantics January 2017

 The term "IPP Printer" is a network entity that accepts IPP operation
 requests and returns IPP operation responses.  As such, an IPP
 Printer object MAY be:
 1.  an (embedded) device component that accepts IPP requests and
     controls the device, or
 2.  a component of a print server that accepts IPP requests (where
     the print server controls one or more networked devices using IPP
     or other protocols).
 Legend:
 ##### indicates a Printer object that is
       either embedded in an Output Device or
       hosted in a server.  The Printer object
       might or might not be capable of queuing/spooling.
 any   indicates any network protocol or direct
       connect, including IPP
 embedded Printer:
                                           Output Device
                                         +---------------+
  O   +--------+                         |  ###########  |
 /|\  | Client |------------IPP------------># Printer #  |
 / \  +--------+                         |  # Object  #  |
                                         |  ###########  |
                                         +---------------+
 hosted Printer:
                                         +---------------+
  O   +--------+        ###########      |               |
 /|\  | Client |--IPP--># Printer #-any->| Output Device |
 / \  +--------+        # Object  #      |               |
                        ###########      +---------------+
                                          +---------------+
 fan out:                                 |               |
                                      +-->| Output Device |
                                  any/    |               |
  O   +--------+      ###########   /     +---------------+
 /|\  | Client |-IPP-># Printer #--*
 / \  +--------+      # Object  #   \     +---------------+
                      ########### any\    |               |
                                      +-->| Output Device |
                                          |               |
                                          +---------------+
               Figure 2: IPP Printer Object Architecture

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3.2. Job Object

 A Job object is used to model a Print Job.  A Job object contains
 zero or more Documents.  The information required to create a Job
 object is sent in a Job Creation request from the End User via an IPP
 Client to the Printer.  The Printer validates the Job Creation
 request, and if the Printer accepts the request, the Printer creates
 the new Job object.  Section 4 describes each of the Job operations
 in detail.
 The characteristics and state of a Job object are described by its
 attributes.  Job attributes are grouped into two groups as follows:
 o  "job-template" attributes: These attributes can be supplied by the
    Client or End User and include Job processing instructions that
    are intended to override any Printer defaults and/or instructions
    embedded within the Document data (see Section 5.2)
 o  "job-description" attributes: These attributes describe the Job's
    identification, state, size, etc.  The Client supplies some of
    these attributes, and the Printer generates others (see
    Section 5.3)
 An implementation MUST support at least one Document per Job object.
 An implementation MAY support multiple Documents per Job object.  A
 Document is either:
 o  a stream of Document data in a format supported by the Printer
    (typically a Page Description Language -- PDL), or
 o  a reference to such a stream of Document data.
 All Job processing instructions are modeled as Job object attributes.
 These attributes are called "Job Template attributes", and they apply
 equally to all Documents within a Job object.

3.3. Object Relationships

 IPP objects have relationships that are maintained persistently along
 with the persistent storage of the object attributes.
 A Printer object can represent either one or more physical Output
 Devices or a Logical Device that "processes" Jobs but never actually
 uses a physical Output Device to put marks on paper.  Examples of
 Logical Devices include a web page publisher or a gateway into an
 online Document archive or repository.  A Printer contains zero or
 more Job objects.

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 A Job object is contained by exactly one Printer; however, the
 identical Document data associated with a Job could be sent to either
 the same or a different Printer.  In this case, a second Job object
 would be created that would be almost identical to the first Job;
 however, it would have new (different) Job object identifiers (see
 Section 3.4).
 A Job either is empty (before any Documents have been added) or
 contains one or more Documents.  If the contained Document is a
 stream of Document data, that stream can be contained in only one
 Document.  However, there can be identical copies of the stream in
 other Documents in the same or different Jobs.  If the contained
 Document is just a reference to a stream of Document data, other
 Documents (in the same or different Job(s)) contain the same
 reference.

3.4. Object Identity

 All IPP objects (Printers, Jobs, etc.) are identified by a Uniform
 Resource Identifier (URI) [RFC3986] so that they can be persistently
 and unambiguously referenced.  Since every URL is a specialized form
 of a URI, even though the more generic term "URI" is used throughout
 the rest of this document, its usage is intended to cover the more
 specific notion of "URL" as well.
 An Administrator configures Printers to either support or not support
 authentication and/or message privacy using Transport Layer Security
 (TLS) [RFC5246]; the mechanism for security configuration is outside
 the scope of this document.  In some situations, both types of
 connections (both authenticated and unauthenticated) can be
 established using a single communication channel that has some sort
 of negotiation mechanism.  In other situations, multiple
 communication channels are used, one for each type of security
 configuration.  Section 9 provides a full description of all security
 considerations and configurations.
 If a Printer supports more than one communication channel, some or
 all of those channels might support and/or require different security
 mechanisms.  In such cases, an Administrator could expose the
 simultaneous support for these multiple communication channels as
 multiple URIs for a single Printer where each URI represents one of
 the communication channels to the Printer.  To support this
 flexibility, the IPP Printer object type defines a multi-valued
 identification attribute called the "printer-uri-supported" attribute
 that MUST contain at least one URI.  The "printer-uri-supported"
 attribute has two companion attributes, the "uri-security-supported"
 attribute and the "uri-authentication-supported" attribute.  Both
 have the same cardinality as "printer-uri-supported".  The purpose of

Sweet & McDonald Standards Track [Page 26] RFC 8011 IPP/1.1: Model and Semantics January 2017

 the "uri-security-supported" attribute is to indicate the security
 mechanisms (if any) used for each URI listed in
 "printer-uri-supported".  The purpose of the
 "uri-authentication-supported" attribute is to indicate the
 authentication mechanisms (if any) used for each URI listed in
 "printer-uri-supported".  These three attributes are fully described
 in Sections 5.4.1, 5.4.2, and 5.4.3.
 When a Job is submitted to the Printer via a Job Creation request,
 the Client supplies only a single Printer URI.  The Client-supplied
 Printer URI MUST be one of the values in the "printer-uri-supported"
 Printer attribute.
 IPP/1.1 does not specify how the Client obtains the Client-supplied
 URI, but it is RECOMMENDED that a Printer be registered as an entry
 in a directory service.  End Users and programs can then interrogate
 the directory, searching for Printers.  Appendix D defines a generic
 schema for Printer object entries in the directory service and
 describes how the entry acts as a bridge to the actual IPP Printer.
 The entry in the directory that represents the IPP Printer includes
 the possibly many URIs for that Printer as values in one of its
 attributes.
 When a Client submits a Job Creation request to the Printer, the
 Printer validates the request and creates a new Job object.  The
 Printer assigns the new Job a numeric identifier that is stored in
 the "job-id" Job attribute and a URI that is stored in the "job-uri"
 Job attribute.  Both the numeric identifier and URI can then be used
 by Clients as the target for subsequent Job operations; the numeric
 identifier is preferred.  The Printer generates the Job numeric
 identifier and URI based on its configured security policy and the
 URI used by the Client in the Job Creation request.
 For example, consider a Printer that supports both a communication
 channel secured by the use of TLS (using HTTP over TLS with an
 "https" schemed URI) and another open communication channel that is
 not secured with TLS (using a simple "http" schemed URI).  If a
 Client submits a Job using the secure URI, the Printer assigns the
 new Job a secure URI as well.  If a Client were to submit a Job using
 the open-channel URI, the Printer might assign the new Job an
 open-channel URI.  Clients SHOULD use the "printer-uri" and "job-id"
 attributes to target a Job to avoid any ambiguity about the security
 of the communication channel.
 In addition, the Printer also populates the Job's "job-printer-uri"
 attribute.  This is a reference back to the Printer that created the
 Job.  If a Client only has access to a Job's "job-uri" identifier,
 the Client can query the Job's "job-printer-uri" attribute in order

Sweet & McDonald Standards Track [Page 27] RFC 8011 IPP/1.1: Model and Semantics January 2017

 to determine which Printer created the Job.  If the Printer supports
 more than one URI, the Printer picks the one URI supplied by the
 Client when creating the Job to build the value for and to populate
 the Job's "job-printer-uri" attribute.
 In addition to identifiers, IPP objects have names -- "printer-name"
 for Printers and "job-name" for Jobs.  An object name is not
 guaranteed to be unique across all instances of all objects.  A
 Printer's name is chosen and set by an Administrator through some
 mechanism outside the scope of this document.  A Job's name can be
 chosen and supplied by the Client submitting the Job.  If the Client
 does not supply a Job name, the Printer generates a name for the new
 Job.  In all cases, the name only has local meaning.
 To summarize:
 o  Each Printer is identified by one or more URIs.  The Printer's
    "printer-uri-supported" attribute contains the URI(s).
 o  The Printer's "uri-security-supported" attribute identifies the
    communication channel security protocols that have been configured
    for the various Printer URIs (e.g., 'tls' or 'none').
 o  The Printer's "uri-authentication-supported" attribute identifies
    the authentication mechanisms that have been configured for the
    various Printer URIs (e.g., 'digest', 'none', etc.).
 o  Each Job is identified by a numeric identifier, which is a 32-bit
    positive integer.  The Job's "job-id" attribute contains the
    Job ID.  The Job ID is only unique within the context of the
    Printer that created the Job.
 o  Each Job is also identified by a URI.  The Job's "job-uri"
    attribute contains the URI, although its use by Clients is
    DEPRECATED.
 o  Each Job has a "job-printer-uri" attribute, which contains the URI
    of the Printer that was used to create the Job.  This attribute is
    used to determine the Printer that created a Job when given only
    the URI for the Job.  This linkage is necessary to determine the
    languages, charsets, and operations that are supported on that Job
    (the basis for such support comes from the creating Printer).
 o  Each Printer has a name, which is not necessarily unique.  The
    Administrator chooses and sets this name through some mechanism
    outside the scope of this IPP/1.1 document.  The Printer's
    "printer-name" attribute contains the name.

Sweet & McDonald Standards Track [Page 28] RFC 8011 IPP/1.1: Model and Semantics January 2017

 o  Each Job has a name, which is not necessarily unique.  The Client
    optionally supplies this name in the Job Creation request.  If the
    Client does not supply this name, the Printer generates a name for
    the Job.  The Job's "job-name" attribute contains the name.

4. IPP Operations

 IPP objects (Printers, Jobs, etc.) support operations.  An operation
 consists of a request and a response.  When a Client communicates
 with a Printer or its Jobs, the Client issues an operation request to
 the Printer URI and object's numeric identifier, if needed.
 Operation requests and responses have parameters that identify the
 operation.  Operations also have attributes that affect the runtime
 characteristics of the operation (the intended target, localization
 information, etc.).  These operation-specific attributes are called
 "operation attributes" (as compared to object attributes such as
 Printer attributes or Job attributes).  Each request carries along
 with it any operation attributes, object attributes, and/or Document
 data required to perform the operation.  Each request requires a
 response from the object.  Each response indicates success or failure
 of the operation with a status-code as a response parameter.  The
 response contains any operation attributes, object attributes, and/or
 status messages generated during the execution of the operation
 request.
 This section describes the semantics of the IPP operations, both
 requests and responses, in terms of the parameters, attributes, and
 other data associated with each operation.
 The Printer operations defined in this document are:
    Print-Job (Section 4.2.1)
    Print-URI (Section 4.2.2)
    Validate-Job (Section 4.2.3)
    Create-Job (Section 4.2.4)
    Get-Printer-Attributes (Section 4.2.5)
    Get-Jobs (Section 4.2.6)
    Pause-Printer (Section 4.2.7)
    Resume-Printer (Section 4.2.8)
    Purge-Jobs (Section 4.2.9)

Sweet & McDonald Standards Track [Page 29] RFC 8011 IPP/1.1: Model and Semantics January 2017

 The Job operations defined in this document are:
    Send-Document (Section 4.3.1)
    Send-URI (Section 4.3.2)
    Cancel-Job (Section 4.3.3)
    Get-Job-Attributes (Section 4.3.4)
    Hold-Job (Section 4.3.5)
    Release-Job (Section 4.3.6)
    Restart-Job (Section 4.3.7)
 The Send-Document and Send-URI Job operations are used to add
 Documents to an existing Job created using the Create-Job operation.

4.1. Common Semantics

 All IPP operations require some common parameters and operation
 attributes.  These common elements and their semantic characteristics
 are defined and described in more detail in the following sections.

4.1.1. Required Parameters

 Every operation request contains the following REQUIRED parameters:
 o  a "version-number",
 o  an "operation-id",
 o  a "request-id", and
 o  the attributes that are REQUIRED for that type of request.
 Every operation response contains the following REQUIRED parameters:
 o  a "version-number",
 o  a "status-code",
 o  the "request-id" that was supplied in the corresponding request,
    and
 o  the attributes that are REQUIRED for that type of response.

Sweet & McDonald Standards Track [Page 30] RFC 8011 IPP/1.1: Model and Semantics January 2017

 The Encoding and Transport document [RFC8010] defines special rules
 for the encoding of these parameters.  All other operation elements
 are represented using the more generic encoding rules for attributes
 and groups of attributes.

4.1.2. Operation IDs and Request IDs

 Each IPP operation request includes an identifying "operation-id"
 value.  Valid values are defined in the "operations-supported"
 Printer attribute section (see Section 5.4.15).  The Client specifies
 which operation is being requested by supplying the correct
 "operation-id" value.
 In addition, every invocation of an operation is identified by a
 "request-id" value.  For each request, the Client chooses the
 "request-id", which MUST be an integer (possibly unique, depending on
 Client requirements) in the range from 1 to 2**31 - 1 (inclusive).
 This "request-id" allows Clients to manage multiple outstanding
 requests.  The receiving IPP object (Printer, Job, etc.) copies all
 32 bits of the Client-supplied "request-id" attribute into the
 response so that the Client can match the response with the correct
 outstanding request, even if the "request-id" is out of range.  If
 the request is terminated before the complete "request-id" is
 received, the IPP object rejects the request and returns a response
 with a "request-id" of 0.
 Note: In some cases, the transport protocol underneath IPP might be a
 connection-oriented protocol that would make it impossible for a
 Client to receive responses in any order other than the order in
 which the corresponding requests were sent.  In such cases, the
 "request-id" attribute would not be essential for correct protocol
 operation.  However, in other transport mappings the operation
 responses could come back in any order, in which case the
 "request-id" is essential.

4.1.3. Attributes

 Operation requests and responses are both composed of groups of
 attributes and/or Document data.  The attribute groups are:
 o  Operation Attributes: These attributes are passed in the operation
    and affect the IPP object's behavior while processing the
    operation request, and they can affect other attributes or groups
    of attributes.  Some operation attributes describe the Document
    data associated with the Print Job and are associated with new Job
    objects; however, most operation attributes do not persist beyond
    the life of the operation.  The description of each operation
    attribute includes conformance statements indicating which

Sweet & McDonald Standards Track [Page 31] RFC 8011 IPP/1.1: Model and Semantics January 2017

    operation attributes are REQUIRED and which are OPTIONAL for an
    IPP object to support, as well as which attributes a Client MUST
    supply in a request and an IPP object MUST supply in a response.
 o  Job Template Attributes: These attributes affect the processing of
    a Job.  A Client MAY supply Job Template attributes in a Job
    Creation request, and the receiving object MUST be prepared to
    receive all supported attributes.  The Job object can later be
    queried to find out what Job Template attributes were originally
    requested in the Job Creation request, and such attributes are
    returned in the response as Job object attributes.  The Printer
    object can be queried about its Job Template attributes to find
    out what type of Job processing capabilities are supported and/or
    what the default Job processing behaviors are, though such
    attributes are returned in the response as Printer object
    attributes.  The "ipp-attribute-fidelity" operation attribute
    affects processing of all Client-supplied Job Template attributes
    -- see Section 4.2.1.1 and Appendix C for a full description of
    "ipp-attribute-fidelity" and its relationship to other attributes.
 o  Job Object Attributes: These attributes are returned in response
    to a query operation directed at a Job object.
 o  Printer Object Attributes: These attributes are returned in
    response to a query operation directed at a Printer object.
 o  Unsupported Attributes: In a Job Creation request, the Client
    supplies a set of operation and Job Template attributes.  If any
    of these attributes or their values are unsupported by the Printer
    object, the Printer object SHOULD return the set of unsupported
    attributes in the response.  Section 4.1.7, Section 4.2.1.2, and
    Appendix C give a full description of how Job Template attributes
    supplied by the Client in a Job Creation request are processed by
    the Printer object and how unsupported attributes are returned to
    the Client.  Because of extensibility, any IPP object might
    receive a request that contains new or unknown attributes or
    values for which it has no support.  In such cases, the IPP object
    processes what it can and returns the unsupported attributes in
    the response.  The Unsupported Attributes group is defined for all
    operation responses for returning unsupported attributes that the
    Client supplied in the request.
 Later in this section, each operation is formally defined by
 identifying the allowed and expected groups of attributes for each
 request and response.  The model identifies a specific order for each
 group in each request or response, but the attributes within each
 group can be in any order, unless specified otherwise.

Sweet & McDonald Standards Track [Page 32] RFC 8011 IPP/1.1: Model and Semantics January 2017

 The attributes within a group MUST be unique; if an attribute with
 the same name occurs more than once, the group is malformed.  Clients
 MUST NOT submit such malformed requests, and Printers MUST NOT return
 such malformed responses.  If such a malformed request is submitted
 to a Printer, the Printer MUST either (1) reject the request with the
 'client-error-bad-request' status-code (RECOMMENDED -- see
 Appendix B.1.4.1) or (2) process the request normally after selecting
 only one of the attribute instances, depending on implementation.
 Which attribute is selected when there are duplicate attributes
 depends on implementation.  The IPP Printer MUST NOT use the values
 from more than one such duplicate attribute instance.
 Each attribute definition includes the attribute's name followed by
 the name of its attribute syntax(es) in parentheses.  In addition,
 each 'integer' attribute can be followed by the allowed range in
 parentheses, (m:n), for values of that attribute.  Each 'text' or
 'name' attribute can be followed by the maximum size in octets in
 parentheses, (size), for values of that attribute.  For more details
 on attribute syntax notation, see the descriptions of these attribute
 syntaxes in Section 5.1.
 Note: Document data included in the operation is not strictly an
 attribute, but it is treated as a special attribute group for
 ordering purposes.  The only operations defined in this document that
 support supplying the Document data within an operation request are
 Print-Job and Send-Document.  There are no operations defined in this
 document whose responses include Document data.
 Some operations are REQUIRED for IPP objects to support; the others
 are OPTIONAL (see Section 6.2.2).  Therefore, before using an
 OPTIONAL operation, a Client SHOULD first use the REQUIRED
 Get-Printer-Attributes operation to query the Printer's
 "operations-supported" attribute in order to determine which OPTIONAL
 operations are actually supported.  The Client SHOULD NOT use an
 OPTIONAL operation that is not supported.  When an IPP object
 receives a request to perform an operation it does not support, it
 MUST return the 'server-error-operation-not-supported' status-code
 (see Appendix B.1.5.2).  An IPP object is non-conformant if it does
 not support a REQUIRED operation.

4.1.4. Character Set and Natural Language Operation Attributes

 Some Job and Printer attributes have values that are text strings and
 names intended for human understanding rather than machine
 understanding (see the 'text' and 'name' attribute syntax
 descriptions in Section 5.1).  The following sections describe two
 special operation attributes called "attributes-charset" and
 "attributes-natural-language" whose values are used when interpreting

Sweet & McDonald Standards Track [Page 33] RFC 8011 IPP/1.1: Model and Semantics January 2017

 other attributes using the 'text' and 'name' attribute syntaxes.  For
 Job Creation operations, the IPP Printer implementation also saves
 these two attributes with the new Job object as Job Status
 attributes.
 The "attributes-charset" and "attributes-natural-language" attributes
 MUST be the first two attributes in every IPP request and response,
 as part of the initial Operation Attributes group of the IPP message.
 The "attributes-charset" attribute MUST be the first attribute in the
 group, and the "attributes-natural-language" attribute MUST be the
 second attribute in the group.
 For the sake of brevity in this document, these operation attribute
 descriptions are not repeated with every operation request and
 response but instead have a reference back to this section.

4.1.4.1. Request Operation Attributes

 The Client MUST supply and the Printer object MUST support the
 following REQUIRED operation attributes in every IPP operation
 request:
 "attributes-charset" (charset):
    This operation attribute identifies the charset (coded character
    set and encoding method) used by any 'text' and 'name' attributes
    that the Client is supplying in this request.  It also identifies
    the charset that the Printer object MUST use (if supported) for
    all 'text' and 'name' attributes and status messages that the
    Printer object returns in the response to this request.  See
    Sections 5.1.2 and 5.1.3 for the definitions of the 'text' and
    'name' attribute syntaxes.
    All Clients and IPP objects MUST support the 'utf-8' charset
    [RFC3629] and MAY support additional charsets, provided that they
    are registered with IANA [RFC2978] [IANA-CS].  If the Printer
    object does not support the Client-supplied charset value, the
    Printer object MUST reject the request, set the
    "attributes-charset" to 'utf-8' in the response, and return the
    'client-error-charset-not-supported' status-code and any 'text' or
    'name' attributes using the 'utf-8' charset.  The Printer MAY
    return any attributes in the Unsupported Attributes group (see
    Sections 4.1.7 and 4.2.1.2).  The Printer object MUST indicate the
    charset(s) supported as the values of the "charset-supported"
    Printer attribute (see Section 5.4.18), so that the Client can
    query to determine which charset(s) is supported.

Sweet & McDonald Standards Track [Page 34] RFC 8011 IPP/1.1: Model and Semantics January 2017

    Note to Client implementors: Since IPP objects are only required
    to support the 'utf-8' charset, in order to maximize
    interoperability with multiple IPP object implementations, a
    Client SHOULD supply 'utf-8' in the "attributes-charset" operation
    attribute, even though the Client is only passing and able to
    present a simpler charset, such as US-ASCII [RFC20] or ISO-8859-1
    [ISO8859-1].  Then the Client will have to filter out, perform
    charset conversion on, or replace those characters that are
    returned in the response that it cannot present to its user.  On
    the other hand, if both the Client and the IPP objects also
    support a charset in common besides 'utf-8', the Client can use
    that charset in order to avoid charset conversion or data loss.
    See the 'charset' attribute syntax description in Section 5.1.8
    for the syntax and semantic interpretation of the values of this
    attribute and for example values.
 "attributes-natural-language" (naturalLanguage):
    This operation attribute identifies the natural language [RFC5646]
    used by any 'text' and 'name' attributes that the Client is
    supplying in this request.  This attribute also identifies the
    natural language that the Printer object SHOULD use for all 'text'
    and 'name' attributes and status messages that the Printer object
    returns in the response to this request.  See the
    'naturalLanguage' attribute syntax description in Section 5.1.9
    for the syntax and semantic interpretation of the values of this
    attribute and for example values.
    There are no REQUIRED natural languages required for the Printer
    object to support.  However, the Printer's
    "generated-natural-language-supported" attribute identifies the
    natural languages supported by the Printer object and any
    contained Jobs for all text strings generated by the IPP object.
    A Client MAY query this attribute to determine which natural
    language(s) is supported for generated messages.
    For any of the attributes for which the Printer object generates
    text, i.e., for the "job-state-message", "printer-state-message",
    and status messages (see Section 4.1.6), the Printer object MUST
    be able to generate these text strings in any of its supported
    natural languages.  If the Client requests a natural language that
    is not supported, the Printer object MUST return these generated
    messages in the Printer's configured natural language as specified
    by the Printer's "natural-language-configured" attribute (see
    Section 5.4.19).

Sweet & McDonald Standards Track [Page 35] RFC 8011 IPP/1.1: Model and Semantics January 2017

    For other 'text' and 'name' attributes supplied by the Client,
    authentication system, Operator, Administrator, or manufacturer
    (i.e., for "job-originating-user-name", "printer-name" (name),
    "printer-location" (text), "printer-info" (text), and
    "printer-make-and-model" (text)), the Printer object is only
    required to support the configured natural language of the Printer
    identified by the Printer's "natural-language-configured"
    attribute, though support of additional natural languages for
    these attributes is permitted.
    For any 'text' or 'name' attribute in the request that is in a
    different natural language than the value supplied in the
    "attributes-natural-language" operation attribute, the Client MUST
    use the Natural Language Override mechanism (see Sections 5.1.2.2
    and 5.1.3.2) for each such attribute value supplied.  The Client
    MAY use the Natural Language Override mechanism redundantly, i.e.,
    use it even when the value is in the same natural language as the
    value supplied in the "attributes-natural-language" operation
    attribute of the request.
    The IPP object MUST accept any natural language and any Natural
    Language Override, whether the IPP object supports that natural
    language or not (and independent of the value of the
    "ipp-attribute-fidelity" operation attribute).  That is, the IPP
    object accepts all Client-supplied values no matter what the
    values are in the Printer's "generated-natural-language-supported"
    attribute.  That attribute,
    "generated-natural-language-supported", only applies to generated
    messages, not Client-supplied messages.  The IPP object MUST
    remember that natural language for all Client-supplied attributes,
    and when returning those attributes in response to a query, the
    IPP object MUST indicate that natural language.
    Each value whose attribute syntax type is 'text' or 'name' (see
    Sections 5.1.2 and 5.1.3) has an Associated Natural Language.
    This document does not specify how this association is stored in a
    Printer or Job object.  When such a value is encoded in a request
    or response, the natural language is either implicit or explicit:
  • In the implicit case, the value contains only the text/name

value, and the language is specified by the

       "attributes-natural-language" operation attribute in the
       request or response (see Sections 5.1.2.1 and 5.1.3.1).
  • In the explicit case (also known as the Natural Language

Override case), the value contains both the language and the

       text/name value (see Sections 5.1.2.2 and 5.1.3.2).

Sweet & McDonald Standards Track [Page 36] RFC 8011 IPP/1.1: Model and Semantics January 2017

    For example, the "job-name" attribute MAY be supplied by the
    Client in a Job Creation request.  The text value for this
    attribute will be in the natural language identified by the
    "attribute-natural-language" attribute, or if different, as
    identified by the Natural Language Override mechanism.  If
    supplied, the IPP object will use the value of the "job-name"
    attribute to populate the Job's "job-name" attribute.  Whenever
    any Client queries the Job's "job-name" attribute, the IPP object
    returns the attribute as stored and uses the Natural Language
    Override mechanism to specify the natural language, if it is
    different from that reported in the "attributes-natural-language"
    operation attribute of the response.  The IPP object MAY use the
    Natural Language Override mechanism redundantly, i.e., use it even
    when the value is in the same natural language as the value
    supplied in the "attributes-natural-language" operation attribute
    of the response.
    An IPP object MUST NOT reject a request based on a supplied
    natural language in an "attributes-natural-language" operation
    attribute or in any attribute that uses the Natural Language
    Override.
    Note: Supplying 'text' or 'name' attributes with an incompatible
    combination of natural language and charset can cause undesired
    behavior.  For example, suppose a Printer supports charsets
    'utf-8', 'iso-8859-1', and 'iso-8859-7'.  Suppose also that it
    supports natural languages 'en' (English), 'fr' (French), and 'el'
    (Greek).  Although the Printer supports the charset 'iso-8859-1'
    and natural language 'el', it probably does not support the
    combination of Greek text strings using the 'iso-8859-1' charset.
    The Printer handles this apparent incompatibility differently,
    depending on the context in which it occurs:
  • In a Job Creation request: If the Client supplies a 'text' or

'name' attribute (for example, the "job-name" operation

       attribute) that uses an apparently incompatible combination, it
       is a Client choice that does not affect the Printer or its
       correct operation.  Therefore, the Printer simply accepts the
       Client-supplied value, stores it with the Job, and responds
       back with the same combination whenever the Client (or any
       Client) queries for that attribute.
  • In a query-type operation, like Get-Printer-Attributes: If the

Client requests an apparently incompatible combination, the

       Printer responds (as described in Section 4.1.4.2) using the
       Printer's configured natural language rather than the natural
       language requested by the Client.

Sweet & McDonald Standards Track [Page 37] RFC 8011 IPP/1.1: Model and Semantics January 2017

    In either case, the Printer does not reject the request because of
    the apparent incompatibility.  The potential incompatible
    combination of charset and natural language can occur either at
    the global operation level or at the Natural Language Override
    attribute-by-attribute level.  In addition, since the response
    always includes explicit charset and natural language information,
    there is never any question or ambiguity in how the Client
    interprets the response.

4.1.4.2. Response Operation Attributes

 The Printer MUST supply and the Client MUST support the following
 REQUIRED operation attributes in every IPP/1.1 operation response:
 "attributes-charset" (charset):
    This operation attribute identifies the charset used by any 'text'
    and 'name' attributes that the Printer object is returning in this
    response.  The value in this response MUST be the same value as
    the "attributes-charset" operation attribute supplied by the
    Client in the request.  If this is not possible (i.e., the charset
    requested is not supported), the request would have been rejected.
    See "attributes-charset" described in Section 4.1.4.1 above.
    If the Printer object supports more than just the 'utf-8' charset,
    the Printer object MUST be able to perform code conversion between
    each of the charsets supported on a "highest fidelity possible"
    basis in order to return the 'text' and 'name' attributes in the
    charset requested by the Client.  However, some information loss
    can occur during the charset conversion, depending on the charsets
    involved.  For example, depending on implementation, the Printer
    object can convert from a UTF-8 'a' to a US-ASCII 'a' (with no
    loss of information); from an ISO Latin 1 CAPITAL LETTER A WITH
    ACUTE ACCENT to US-ASCII 'A' (losing the accent); or from a UTF-8
    Japanese Kanji character to some ISO Latin 1 error character
    indication such as '?', a decimal code equivalent, or the absence
    of a character.
    Whether an implementation that supports more than one charset
    stores the data in the charset supplied by the Client or performs
    code conversion to one of the other supported charsets depends on
    implementation.  The strategy should try to minimize loss of
    information during code conversion.  On each response, such an
    implementation converts from its internal charset to that
    requested.

Sweet & McDonald Standards Track [Page 38] RFC 8011 IPP/1.1: Model and Semantics January 2017

 "attributes-natural-language" (naturalLanguage):
    This operation attribute identifies the natural language used by
    any 'text' and 'name' attributes that the IPP object is returning
    in this response.  Unlike the "attributes-charset" operation
    attribute, the IPP object MAY return the natural language of the
    Job object or the Printer's configured natural language as
    identified by the Printer's "natural-language-configured"
    attribute, rather than the natural language supplied by the
    Client.  For any 'text' or 'name' attribute or status message in
    the response that is in a different natural language than the
    value returned in the "attributes-natural-language" operation
    attribute, the IPP object MUST use the Natural Language Override
    mechanism (see Sections 5.1.2.2 and 5.1.3.2) on each attribute
    value returned.  The IPP object MAY use the Natural Language
    Override mechanism redundantly, i.e., use it even when the value
    is in the same natural language as the value supplied in the
    "attributes-natural-language" operation attribute of the response.

4.1.5. Operation Targets

 All IPP operations are directed at IPP objects.  For Printer
 operations, the operation is always directed at a Printer object
 using one of its URIs, i.e., one of the values in the Printer's
 "printer-uri-supported" attribute.  Even if the Printer object
 supports more than one URI, the Client supplies only one URI as the
 target of the operation.  The Client identifies the target object by
 supplying the correct URI in the "printer-uri" operation attribute.
 For Job operations, the operation is directed at either:
 o  The Printer object that created the Job object using the Printer
    object's URI and the Job's numeric identifier (Job ID).  Since the
    Printer object that created the Job object generated the Job ID,
    it MUST be able to correctly associate the Client-supplied Job ID
    with the correct Job object.  The Client supplies the Printer's
    URI in the "printer-uri" operation attribute and the Job ID in the
    "job-id" operation attribute.
 o  The Job object itself using the Job's URI.  In this case, the
    Client identifies the target object by supplying the correct URI
    in the "job-uri" (uri) operation attribute (Section 5.3.2).
 Clients SHOULD send the "printer-uri" and "job-id" operation
 attributes in Job operations.

Sweet & McDonald Standards Track [Page 39] RFC 8011 IPP/1.1: Model and Semantics January 2017

 If the operation is directed at the Job object directly using the
 Job's URI, the Client MUST NOT include the redundant "job-id"
 operation attribute.
 The operation target attributes are REQUIRED operation attributes
 that are included in every operation request.  Like the charset and
 natural language attributes (see Section 4.1.4), the operation target
 attributes are specially ordered operation attributes.  In all cases,
 the operation target attributes immediately follow the
 "attributes-charset" and "attributes-natural-language" attributes
 within the Operation Attributes group; however, the specific ordering
 rules are as follows:
 o  In the case where there is only one operation target attribute
    (i.e., either only the "printer-uri" attribute or only the
    "job-uri" attribute), that attribute MUST be the third attribute
    in the Operation Attributes group.
 o  In the case where Job operations use two operation target
    attributes (i.e., the "printer-uri" and "job-id" attributes), the
    "printer-uri" attribute MUST be the third attribute and the
    "job-id" attribute MUST be the fourth attribute.
 In all cases, the target URIs contained within the body of IPP
 operation requests and responses MUST be in absolute format rather
 than relative format (a relative URL identifies a resource with the
 scope of the HTTP server, but does not include scheme, host,
 or port).
 The following rules apply to the use of port numbers in URIs that
 identify IPP objects:
 1.  If the URI scheme allows the port number to be explicitly
     included in the URI string, and a port number is specified within
     the URI, then that port number MUST be used by the Client to
     contact the IPP object.
 2.  If the URI scheme allows the port number to be explicitly
     included in the URI string, and a port number is not specified
     within the URI, then the default port number implied by that URI
     scheme MUST be used by the Client to contact the IPP object.
 3.  If the URI scheme does not allow an explicit port number to be
     specified within the URI, then the default port number implied by
     that URI MUST be used by the Client to contact the IPP object.

Sweet & McDonald Standards Track [Page 40] RFC 8011 IPP/1.1: Model and Semantics January 2017

 Note: "Internet Printing Protocol/1.1: IPP URL Scheme" [RFC3510] and
 "Internet Printing Protocol (IPP) over HTTPS Transport Binding and
 the 'ipps' URI Scheme" [RFC7472] define the mapping of IPP onto HTTP
 and HTTPS, respectively, and define and register a default port
 number.

4.1.6. Operation Response Status-Code Values and Status Messages

 Every operation response includes a REQUIRED "status-code" parameter,
 SHOULD include the "status-message" operation attribute, and MAY
 include the "detailed-status-message" operation attribute.  The
 Print-URI and Send-URI response MAY also include the
 "document-access-error" operation attribute.

4.1.6.1. "status-code" (type2 enum)

 The REQUIRED "status-code" parameter provides information on the
 processing of a request.
 The status-code is intended for use by automata.  A Client
 implementation of IPP SHOULD convert status-code values into any
 localized message that has semantic meaning to the End User.
 The "status-code" value is a numeric value that has semantic meaning.
 The "status-code" syntax is similar to a "type2 enum" (see
 Section 5.1 ("Attribute Syntaxes")), except that values can range
 only from 0x0000 to 0x7fff.  Appendix B describes and assigns the
 status-code values, and suggests a corresponding status message for
 each status-code for use by the Client when the user's natural
 language is English.
 If the Printer performs an operation with no errors and it encounters
 no problems, it MUST return the status-code 'successful-ok' in the
 response.  See Appendix B.

Sweet & McDonald Standards Track [Page 41] RFC 8011 IPP/1.1: Model and Semantics January 2017

 If the Client supplies unsupported values for the following
 parameters or operation attributes, the Printer object MUST reject
 the operation, MAY return the unsupported attribute value in the
 Unsupported Attributes group, and MUST return the indicated
 status-code:
 +---------------------+---------------------------------------------+
 | Parameter/Attribute | Status-Code                                 |
 +---------------------+---------------------------------------------+
 | version-number      | server-error-version-not-supported          |
 +---------------------+---------------------------------------------+
 | operation-id        | server-error-operation-not-supported        |
 +---------------------+---------------------------------------------+
 | attributes-charset  | client-error-charset-not-supported          |
 +---------------------+---------------------------------------------+
 | compression         | client-error-compression-not-supported      |
 +---------------------+---------------------------------------------+
 | document-format     | client-error-document-format-not-supported  |
 +---------------------+---------------------------------------------+
 | document-uri        | client-error-uri-scheme-not-supported,      |
 |                     | client-error-document-access-error          |
 +---------------------+---------------------------------------------+
             Table 1: Status-Code Values for All Requests
 If the Client supplies unsupported values for other attributes, or
 unsupported attributes, the Printer returns the status-code defined
 in Section 4.1.7 ("Unsupported Attributes").

4.1.6.2. "status-message" (text(255))

 The RECOMMENDED "status-message" operation attribute provides a short
 textual description of the status of the operation.  The
 "status-message" attribute's syntax is "text(255)", so the maximum
 length is 255 octets (see Section 5.1.2).  The status message is
 intended for the human End User.  If a response does include a
 "status-message" attribute, an IPP Client can examine or display the
 messages in some implementation-specific manner.  The
 "status-message" attribute is especially useful for a later version
 of a Printer to return as supplemental information for the human
 user, to accompany a status-code that an earlier version of a Client
 might not understand.
 If the Printer supports the "status-message" operation attribute, it
 MUST be able to generate this message in any of the natural languages
 identified by the Printer's "generated-natural-language-supported"
 attribute and MUST honor any supported value for the
 "attributes-natural-language" operation attribute (Section 4.1.4.1)

Sweet & McDonald Standards Track [Page 42] RFC 8011 IPP/1.1: Model and Semantics January 2017

 of the Client request.  Appendix B suggests the text for the status
 message returned by the Printer for use with the English natural
 language.
 As described in Section 4.1.4.1, for any returned 'text' attribute,
 if there is a choice for generating this message, the Printer uses
 the natural language indicated by the value of
 "attributes-natural-language" in the Client request, if supported;
 otherwise, the Printer uses the value in the Printer's own
 "natural-language-configured" attribute.
 If the Printer supports the "status-message" operation attribute, it
 SHOULD use the REQUIRED 'utf-8' charset to return a status message
 for the following error status-code values (see Appendix B):
 'client-error-bad-request', 'client-error-charset-not-supported',
 'server-error-internal-error',
 'server-error-operation-not-supported', and
 'server-error-version-not-supported'.  In this case, it MUST set the
 value of the "attributes-charset" operation attribute to 'utf-8' in
 the error response.

4.1.6.3. "detailed-status-message" (text(MAX))

 The OPTIONAL "detailed-status-message" operation attribute provides
 additional more-detailed technical and implementation-specific
 information about the operation for Administrators or other
 experienced technical people.  The "detailed-status-message"
 attribute's syntax is "text(MAX)", so the maximum length is
 1023 octets (see Section 5.1.2).  If the Printer supports the
 "detailed-status-message" operation attribute, the Printer SHOULD
 localize the message, unless such localization would obscure the
 technical meaning of the message.  Clients MUST NOT attempt to parse
 the value of this attribute.  See the "document-access-error"
 operation attribute (Section 4.1.6.4) for additional errors that a
 program can process.

4.1.6.4. "document-access-error" (text(MAX))

 This OPTIONAL operation attribute provides additional information
 about any Document access errors encountered by the Printer before it
 returned a response to the Print-URI (Section 4.2.2) or Send-URI
 (Section 4.3.2) operation.  For errors in the protocol identified by
 the URI scheme in the "document-uri" operation attribute, such as
 'http:' or 'ftp:', the error code is returned in parentheses,
 followed by the URI.  For example:
 (404) http://www.example.com/filename.pdf

Sweet & McDonald Standards Track [Page 43] RFC 8011 IPP/1.1: Model and Semantics January 2017

 Most Internet protocols use decimal error codes (unlike IPP), so the
 ASCII error code representation is in decimal.

4.1.7. Unsupported Attributes

 The Unsupported Attributes group contains attributes that are not
 supported by the operation.  This group is primarily for the Job
 Creation operations, but all operations can return this group.
 A Printer MUST include an Unsupported Attributes group in a response
 if the status-code is one of the following:
 'successful-ok-ignored-or-substituted-attributes',
 'successful-ok-conflicting-attributes',
 'client-error-attributes-or-values-not-supported', or
 'client-error-conflicting-attributes'.
 If the status-code is one of the four specified in the preceding
 paragraph, the Unsupported Attributes group MUST contain all of those
 attributes and only those attributes that are:
 a.  an operation or Job Template attribute supplied in the request,
     and
 b.  unsupported by the Printer.  See below for details on the three
     categories of "unsupported" attributes.
 If the status-code is one of those in Table 1 in Section 4.1.6.1, the
 OPTIONAL Unsupported Attributes group contains the unsupported
 parameter or attribute indicated in that table.
 If the Printer is not returning any unsupported attributes in the
 response, the Printer SHOULD omit the Unsupported Attributes group
 rather than sending an empty group.  However, a Client MUST be able
 to accept an empty group.
 Unsupported attributes fall into three categories:
 1.  The Printer does not support the supplied attribute (no matter
     what the attribute syntax or value).
 2.  The Printer does support the attribute, but it does not support
     some or all of the particular attribute syntaxes or values
     supplied by the Client, i.e., the Printer does not have those
     attribute syntaxes or values in its corresponding "xxx-supported"
     attribute.

Sweet & McDonald Standards Track [Page 44] RFC 8011 IPP/1.1: Model and Semantics January 2017

 3.  The Printer does support the attributes and values supplied, but
     the particular values are in conflict with one another, because
     they violate a constraint, such as not being able to staple
     transparencies.
 In the case of an unsupported attribute name, the Printer returns the
 Client-supplied attribute with a substituted value of 'unsupported'.
 This value's syntax type is "out-of-band", and its encoding is
 defined by special rules for "out-of-band" values in the Encoding and
 Transport document [RFC8010].  Its value indicates no support for the
 attribute itself -- see the beginning of Section 5.1 in this
 document.
 In the case of a supported attribute with one or more unsupported
 attribute syntaxes or values, the Printer simply returns the
 Client-supplied attribute with the unsupported attribute syntaxes or
 values as supplied by the Client.  This indicates support for the
 attribute but no support for that particular attribute syntax or
 value.  If the Client supplies a multi-valued attribute with more
 than one value and the Printer supports the attribute but only
 supports a subset of the Client-supplied attribute syntaxes or
 values, the Printer MUST return only those attribute syntaxes or
 values that are unsupported.
 In the case of two (or more) supported attribute values that are in
 conflict with one another (although each is supported independently,
 the values conflict when requested together within the same Job), the
 Printer MUST return all the values that it ignores or substitutes to
 resolve the conflict but not any of the values that it is still
 using.  The choice for exactly how to resolve the conflict is
 implementation dependent.  See Section 4.2.1.2 and Appendix C.  See
 the Implementor's Guides [RFC3196] [PWG5100.19] for examples.

4.1.8. Versions

 Each operation request and response carries with it a
 "version-number" parameter.  Each value of the "version-number"
 parameter is in the form "X.Y" where X is the major version number
 and Y is the minor version number.  By including a version number in
 the Client request, it allows the Client to identify which version of
 IPP it is interested in using, i.e., the version whose conformance
 requirements the Client can depend upon the Printer to meet.
 If the IPP object does not support that major version number supplied
 by the Client, i.e., the "major version number" portion of the
 "version-number" parameter does not match any of the values of the
 Printer's "ipp-versions-supported" attribute (see Section 5.4.14),
 the object MUST respond with a status-code of

Sweet & McDonald Standards Track [Page 45] RFC 8011 IPP/1.1: Model and Semantics January 2017

 'server-error-version-not-supported' along with the closest version
 number that is supported (see Appendix B.1.5.4).  If the major
 version number is supported but the minor version number is not, the
 IPP object SHOULD accept the request and attempt to perform it (or
 reject the request if the operation is not supported); otherwise, it
 rejects the request and returns the
 'server-error-version-not-supported' status-code.  In all cases, the
 IPP object MUST return the "version-number" value that it supports
 that is closest to the version number supplied by the Client in the
 request.
 There is no version negotiation per se.  However, if a Client has
 received a 'server-error-version-not-supported' status-code from an
 IPP object, the Client SHOULD try again with a different version
 number.  A Client MAY also determine the versions supported either
 from a directory that conforms to Appendix D or by querying the
 Printer's "ipp-versions-supported" attribute (see Section 5.4.14) to
 determine which versions are supported.
 An IPP/1.1 object implementation MUST support version '1.1', i.e.,
 meet the conformance requirements for IPP/1.1 as specified in this
 document and [RFC8010].  IPP implementations SHOULD accept any
 request with the major version '1' or '2', or reject the request if
 the operation is not supported.
 There is only one notion of "version number" that covers both IPP
 Model and IPP protocol changes.  Changes to the major version number
 of the Model and Semantics document can indicate structural or
 syntactic changes that make it impossible for older versions of IPP
 Clients and Printers to correctly parse and correctly process the new
 or changed attributes, operations, and responses.  If the major
 version number changes, the minor version number is set to zero.  As
 an example, adding the REQUIRED "ipp-attribute-fidelity" attribute to
 version '1.1' (if it had not been part of version '1.0') would have
 required a change to the major version number, since an IPP/1.0
 Printer would not have processed a request with the correct semantics
 that contained the "ipp-attribute-fidelity" attribute that it did not
 know about.  Items that might affect the changing of the major
 version number include any changes to the Model and Semantics
 document (this document) or the Encoding and Transport document
 [RFC8010] itself, such as:
 o  reordering of ordered attributes or attribute sets
 o  changes to the syntax of existing attributes
 o  adding REQUIRED (for an IPP object to support) Operation
    Attributes groups

Sweet & McDonald Standards Track [Page 46] RFC 8011 IPP/1.1: Model and Semantics January 2017

 o  adding values to existing REQUIRED operation attributes
 o  adding REQUIRED operations
 Changes to the minor version number indicate the addition of new
 features, attributes, and attribute values that might not be
 understood by all IPP objects but that can be ignored if not
 understood.  Items that might affect the changing of the minor
 version number include any changes to the model objects and
 attributes but not the encoding and transport rules [RFC8010] (except
 adding attribute syntaxes).  Examples of such changes are:
 o  grouping all extensions not included in a previous version into a
    new version
 o  adding new attribute values
 o  adding new object attributes
 o  adding OPTIONAL (for an IPP object to support) operation
    attributes (i.e., those attributes that an IPP object can ignore
    without confusing Clients)
 o  adding OPTIONAL (for an IPP object to support) Operation
    Attributes groups (i.e., those attributes that an IPP object can
    ignore without confusing Clients)
 o  adding new attribute syntaxes
 o  adding OPTIONAL operations
 o  changing Job attributes or Printer attributes from OPTIONAL to
    REQUIRED or vice versa
 o  adding OPTIONAL attribute syntaxes to an existing attribute
 The encoding [RFC8010] of the "version-number" parameter MUST NOT
 change over any version number (either major or minor).  This rule
 guarantees that all future versions will be backwards compatible with
 all previous versions (at least for checking the "version-number"
 parameter).  In addition, any protocol elements (attributes, error
 codes, tags, etc.) that are not carried forward from one version to
 the next are DEPRECATED so that they can never be reused with new
 semantics.

Sweet & McDonald Standards Track [Page 47] RFC 8011 IPP/1.1: Model and Semantics January 2017

 Implementations that support a certain version SHOULD support all
 previous Standards Track versions.  As each new version is defined
 (through the release of a new IPP specification document), that
 version will specify which previous versions MUST and which versions
 SHOULD be supported in compliant implementations.

4.1.9. Job Creation Operations

 In order to "submit a Print Job" and create a new Job, a Client
 issues a Job Creation request.  A Job Creation request is any one of
 the following three operation requests:
 o  The Print-Job Request: A Client that wants to submit a Print Job
    with only a single Document can use the Print-Job operation.  The
    operation allows for the Client to "push" the Document data to the
    Printer by including the Document data in the request itself.
    Note that Clients SHOULD instead use the Create-Job and
    Send-Document requests, if supported by the Printer, since they
    allow for Job monitoring and control during submission of the
    Document data.
 o  The Print-URI Request: A Client that wants to submit a Print Job
    with only a single Document (where the Printer "pulls" the
    Document data instead of the Client "pushing" the data to the
    Printer) uses the Print-URI operation.  In this case, the Client
    includes in the request only a URI reference to the Document data
    (not the Document data itself).
 o  The Create-Job Request: A Client that wants to submit a Print Job
    with zero or more Documents uses the Create-Job operation.  This
    operation is followed by an arbitrary number of Send-Document
    and/or Send-URI operations, each creating another Document for the
    newly created Job.  The Send-Document operation includes the
    Document data in the request (the Client "pushes" the Document
    data to the Printer), and the Send-URI operation includes only a
    URI reference to the Document data in the request (the Printer
    "pulls" the Document data from the referenced location).  The last
    Send-Document or Send-URI request for a given Job includes a
    "last-document" operation attribute set to 'true' indicating that
    this is the last request.
 Throughout this document, the term "Job Creation request" is used to
 refer to any of these three operation requests.
 A Create-Job operation followed by only one Send-Document operation
 is semantically equivalent to a Print-Job operation; however, the
 Client SHOULD use the Create-Job and Send-Document operations (when
 supported) for all Jobs with a single Document to allow for reliable

Sweet & McDonald Standards Track [Page 48] RFC 8011 IPP/1.1: Model and Semantics January 2017

 Job control and monitoring.  Print-Job is a REQUIRED operation (all
 implementations MUST support it), whereas Create-Job is a RECOMMENDED
 operation and hence some implementations might not support it.
 Job submission time is the point in time when a Client issues a Job
 Creation request.  The initial state of every Job is the 'pending',
 'pending-held', or 'processing' state (see Section 5.3.7).  When the
 Printer begins processing the Print Job, the Job's state moves to
 'processing'.  This is known as Job processing time.
 At Job submission time and at the time a Validate-Job operation is
 received, the Printer MUST do the following:
 1.  Process the Client-supplied attributes and either accept or
     reject the request
 2.  Validate the syntax of and support for the scheme of any
     Client-supplied URI
 At Job submission time, the Printer MUST validate whether the
 supplied attributes, attribute syntaxes, and values are supported by
 matching them with the Printer's corresponding "xxx-supported"
 attributes.  See Section 4.1.7 for details.  See the Implementor's
 Guides [RFC3196] [PWG5100.19] for guidance on processing Job Creation
 requests.
 At Job submission time, the Printer MAY perform the validation checks
 reserved for Job processing time, such as:
 1.  Validating the format of the Document data
 2.  Validating the actual contents of any Client-supplied URI
     (resolve the reference and follow the link to the Document data)
 At Job submission time, these additional Job processing time
 validation checks are essentially useless, since they require
 actually parsing and interpreting the Document data, are not
 guaranteed to be 100% accurate, and MUST be done, yet again, at Job
 processing time.  Also, in the case of a URI, checking for
 availability at Job submission time does not guarantee availability
 at Job processing time.  In addition, at Job processing time, the
 Printer might discover any of the following conditions that were not
 detectable at Job submission time:
 o  runtime errors in the Document data,
 o  nested Document data that is in an unsupported format,

Sweet & McDonald Standards Track [Page 49] RFC 8011 IPP/1.1: Model and Semantics January 2017

 o  the URI reference is no longer valid (i.e., the server hosting the
    Document might be down), or
 o  any other Job processing error.
 At Job submission time, a Printer, especially a non-spooling Printer,
 MAY accept Jobs for which it does not have enough space.  In such a
 situation, a Printer MAY stop reading data from a Client for an
 indefinite period of time.  A Client MUST be prepared for a write
 operation to block for an indefinite period of time (see Section 6.1
 ("Client Conformance Requirements")).
 When a Printer has too little space for starting a new Job, it MAY
 reject a new Job Creation request.  In this case, a Printer MUST
 return a response (in reply to the rejected request) with a
 status-code of 'server-error-busy' (see Appendix B.1.5.8), and it MAY
 close the connection before receiving all bytes of the operation.  A
 Printer SHOULD indicate that it is temporarily unable to accept Jobs
 by setting the 'spool-space-full' value in its
 "printer-state-reasons" attribute and removing the value when it can
 accept another Job (see Section 5.4.12).
 When receiving a 'server-error-busy' status-code in an operation
 response, a Client MUST be prepared for the Printer to close the
 connection before the Client has sent all of the data (especially for
 the Print-Job operation).  A Client MUST be prepared to keep
 submitting a Job Creation request until the Printer accepts the Job
 Creation request.
 At Job processing time, since the Printer has already responded with
 a successful status-code in the response to the Job Creation request,
 if the Printer detects an error, the Printer is unable to inform the
 End User of the error with an operation status-code.  In this case,
 the Printer, depending on the error, can set the Job's "job-state",
 "job-state-reasons", and/or "job-state-message" attributes to the
 appropriate value(s) so that later queries can report the correct Job
 status.
 Note: Asynchronous notification of events is defined in "Internet
 Printing Protocol (IPP): Event Notifications and Subscriptions"
 [RFC3995].

4.2. Printer Operations

 All Printer operations are directed at Printers.  A Client MUST
 always supply the "printer-uri" operation attribute in order to
 identify the correct target of the operation.

Sweet & McDonald Standards Track [Page 50] RFC 8011 IPP/1.1: Model and Semantics January 2017

4.2.1. Print-Job Operation

 This REQUIRED operation allows a Client to submit a Print Job with
 only one Document and supply the Document data (rather than just a
 reference to the data).  See Appendix C for the suggested steps for
 processing Job Creation requests and their operation and Job Template
 attributes.

4.2.1.1. Print-Job Request

 The following groups of attributes are supplied as part of the
 Print-Job request:
 Group 1: Operation Attributes
    Natural Language and Character Set:
       The "attributes-charset" and "attributes-natural-language"
       attributes as described in Section 4.1.4.1.  The Printer MUST
       copy these values to the corresponding Job Status attributes
       described in Sections 5.3.19 and 5.3.20.
    Target:
       The "printer-uri" (uri) operation attribute, which is the
       target for this operation as described in Section 4.1.5.
    Requesting User Name:
       The "requesting-user-name" (name(MAX)) attribute SHOULD be
       supplied by the Client as described in Section 9.3.
    "job-name" (name(MAX)):
       The Client MAY supply and the Printer MUST support this
       attribute.  It contains the Client-supplied Job name.  If this
       attribute is supplied by the Client, its value is used for the
       "job-name" attribute of the newly created Job.  The Client MAY
       automatically include any information that will help the
       End User distinguish amongst his/her Jobs, such as the name of
       the application program along with information from the
       Document, such as the Document name, Document subject, or
       source file name.  If this attribute is not supplied by the
       Client, the Printer generates a name to use in the "job-name"
       attribute of the newly created Job (see Section 5.3.5).

Sweet & McDonald Standards Track [Page 51] RFC 8011 IPP/1.1: Model and Semantics January 2017

    "ipp-attribute-fidelity" (boolean):
       The Client MAY supply and the Printer MUST support this
       attribute.  The value 'true' indicates that total fidelity to
       Client-supplied Job Template attributes and values is required;
       otherwise, the Printer MUST reject the Print-Job request.  The
       value 'false' indicates that a reasonable attempt to print the
       Job is acceptable and the Printer MUST accept the Print-Job
       request.  If not supplied, the Printer assumes that the value
       is 'false'.  All Printers MUST support both types of Job
       processing.  See Appendix C for a full description of
       "ipp-attribute-fidelity" and its relationship to other
       attributes, especially the Printer's "pdl-override-supported"
       attribute.
    "document-name" (name(MAX)):
       The Client MAY supply and the Printer MUST support this
       attribute.  It contains the Client-supplied Document name.  The
       Document name MAY be different than the Job name.  Typically,
       the Client software automatically supplies the Document name on
       behalf of the End User by using a file name or an
       application-generated name.  If this attribute is supplied, its
       value can be used in a manner defined by each implementation.
       Examples include the following: printed along with the Job (Job
       start sheet, page adornments, etc.), used by accounting or
       resource-tracking management tools, or even stored along with
       the Document as a Document-level attribute.
    "compression" (type2 keyword):
       The Client MAY supply and the Printer MUST support this
       attribute.  The Client-supplied "compression" operation
       attribute identifies the compression algorithm used on the
       Document data.  The following cases exist:
       a.  If the Client omits this attribute, the Printer MUST assume
           that the data is not compressed, i.e., the Printer follows
           the rules below as if the Client supplied the "compression"
           attribute with a value of 'none'.
       b.  If the Client supplies this attribute but the value is not
           supported by the Printer, i.e., the value is not one of the
           values of the Printer's "compression-supported" attribute,
           the Printer MUST reject the request and return the
           'client-error-compression-not-supported' status-code.  See
           Section 4.1.7 for details on returning unsupported
           attributes and values.

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       c.  If the Client supplies the attribute and the Printer
           supports the attribute value, the Printer uses the
           corresponding decompression algorithm on the Document data.
       d.  If the decompression algorithm fails before the Printer
           returns an operation response, the Printer MUST reject the
           request and return the 'client-error-compression-error'
           status-code.
       e.  If the decompression algorithm fails after the Printer
           returns an operation response, the Printer MUST abort the
           Job and add the 'compression-error' value to the Job's
           "job-state-reasons" attribute.
       f.  If the decompression algorithm succeeds, the Document data
           MUST then have the format specified by the Job's
           "document-format" attribute, if supplied (see the
           "document-format" operation attribute definition below).
    "document-format" (mimeMediaType):
       The Client MAY supply and the Printer MUST support this
       attribute.  The value identifies the format of the supplied
       Document data.  The following cases exist:
       a.  If the Client does not supply this attribute, the Printer
           assumes that the Document data is in the format defined by
           the Printer's "document-format-default" attribute (i.e.,
           the Printer follows the rules below as if the Client
           supplied the "document-format" attribute with a value equal
           to the Printer's default value).
       b.  If the Client supplies this attribute but the value is not
           supported by the Printer, i.e., the value is not one of the
           values of the Printer's "document-format-supported"
           attribute, the Printer MUST reject the request and return
           the 'client-error-document-format-not-supported'
           status-code.
       c.  If the Client supplies this attribute and its value is
           'application/octet-stream' (i.e., to be auto-sensed; see
           Section 5.1.10.1), and the format is not one of the
           Document formats that the Printer can auto-sense, and this
           check occurs before the Printer returns an operation
           response, then the Printer MUST reject the request and
           return the 'client-error-document-format-not-supported'
           status-code.

Sweet & McDonald Standards Track [Page 53] RFC 8011 IPP/1.1: Model and Semantics January 2017

       d.  If the Client supplies this attribute and the value is
           supported by the Printer, the Printer is capable of
           interpreting the Document data.
       e.  If interpretation of the Document data fails before the
           Printer returns an operation response, the Printer MUST
           reject the request and return the
           'client-error-document-format-error' status-code.
       f.  If interpretation of the Document data fails after the
           Printer returns an operation response, the Printer MUST
           abort the Job and add the 'document-format-error' value to
           the Job's "job-state-reasons" attribute.
    "document-natural-language" (naturalLanguage):
       The Client MAY supply and the Printer SHOULD support this
       attribute.  The value specifies the natural language of the
       Document content for those Document formats that require a
       specification of the natural language in order to properly
       image the Document.
    "job-k-octets" (integer(0:MAX)):
       The Client MAY supply and the Printer SHOULD support this
       attribute.  The Client-supplied "job-k-octets" operation
       attribute identifies the total size of the Document(s) in
       K octets being submitted (see Section 5.3.17.1 for the complete
       semantics).  If the Client supplies the attribute and the
       Printer supports the attribute, the value of the attribute is
       used to populate the Job's "job-k-octets" Job Description
       attribute.
       For this attribute and the following two attributes
       ("job-impressions" and "job-media-sheets"), if the Client
       supplies the attribute but the Printer does not support the
       attribute, the Printer ignores the Client-supplied value.  If
       the Client supplies the attribute and the Printer supports the
       attribute, and the value is within the range of the
       corresponding Printer's "xxx-supported" attribute, the Printer
       MUST use the value to populate the Job's "xxx" attribute.  If
       the Client supplies the attribute and the Printer supports the
       attribute, but the value is outside the range of the
       corresponding Printer's "xxx-supported" attribute, the Printer
       MUST copy the attribute and its value to the Unsupported
       Attributes group, reject the request, and return the
       'client-error-attributes-or-values-not-supported' status-code.
       If the Client does not supply the attribute, the Printer SHOULD

Sweet & McDonald Standards Track [Page 54] RFC 8011 IPP/1.1: Model and Semantics January 2017

       populate the corresponding Job attribute if it supports the
       attribute and is able to calculate or discern the correct
       value.
    "job-impressions" (integer(0:MAX)):
       The Client MAY supply and the Printer SHOULD support this
       attribute.  The Client-supplied "job-impressions" operation
       attribute identifies the total size in number of Impressions of
       the Document(s) being submitted (see Section 5.3.17.2 for the
       complete semantics).
       See the last paragraph under "job-k-octets".
    "job-media-sheets" (integer(1:MAX)):
       The Client MAY supply and the Printer SHOULD support this
       attribute.  The Client-supplied "job-media-sheets" operation
       attribute identifies the total number of Media Sheets to be
       produced for this Job (see Section 5.3.17.3 for the complete
       semantics).
       See the last paragraph under "job-k-octets".
 Group 2: Job Template Attributes
    The Client MAY supply a set of Job Template attributes as defined
    in Section 5.2.  If the Client is not supplying any Job Template
    attributes in the request, the Client SHOULD omit Group 2 rather
    than sending an empty group.  However, a Printer MUST be able to
    accept an empty group.
 Group 3: Document Data
    The Client MUST supply the Document data to be processed.
 The simplest Print-Job request consists of just the
 "attributes-charset" and "attributes-natural-language" operation
 attributes, the "printer-uri" target operation attribute, and the
 Document data.  In this simple case, the Printer:
 o  creates a new Job containing a single Document,
 o  stores a generated Job name in the "job-name" attribute in the
    natural language and charset requested (see Section 4.1.4.1) (if
    those are supported; otherwise, using the Printer's default
    natural language and charset), and

Sweet & McDonald Standards Track [Page 55] RFC 8011 IPP/1.1: Model and Semantics January 2017

 o  at Job processing time, uses its corresponding default value
    attributes for the supported Job Template attributes that were not
    supplied by the Client as an IPP attribute or embedded
    instructions in the Document data.

4.2.1.2. Print-Job Response

 The Printer MUST return to the Client the following sets of
 attributes as part of the Print-Job response:
 Group 1: Operation Attributes
    Natural Language and Character Set:
       The "attributes-charset" and "attributes-natural-language"
       attributes as described in Section 4.1.4.2.
    Status Message:
       In addition to the REQUIRED status-code returned in every
       response, the response MAY include a "status-message"
       (text(255)) and/or a "detailed-status-message" (text(MAX))
       operation attribute as described in Appendix B and
       Section 4.1.6.  If the Client supplies unsupported or
       conflicting Job Template attributes or values, the Printer MUST
       reject or accept the Print-Job request, depending on whether
       the Client supplied a 'true' or 'false' value for the
       "ipp-attribute-fidelity" operation attribute.  See the
       Implementor's Guides [RFC3196] [PWG5100.19] for guidance on
       processing Job Creation requests.
 Group 2: Unsupported Attributes
    See Section 4.1.7 for details on returning unsupported attributes.
    The value of "ipp-attribute-fidelity" supplied by the Client does
    not affect what attributes the Printer returns in this group.  The
    value of "ipp-attribute-fidelity" only affects whether the
    Print-Job operation is accepted or rejected.  If the Job is
    accepted, the Client can query the Job using the
    Get-Job-Attributes operation, requesting the unsupported
    attributes that were returned in the Print-Job response to see
    which attributes were ignored (not stored in the Job) and which
    attributes were stored with other (substituted) values.

Sweet & McDonald Standards Track [Page 56] RFC 8011 IPP/1.1: Model and Semantics January 2017

 Group 3: Job Attributes
    "job-id" (integer(1:MAX)):
       The Printer MUST return the Job's ID in the REQUIRED "job-id"
       Job attribute.  The Client uses this "job-id" attribute in
       conjunction with the "printer-uri" attribute used in the
       Print-Job request when directing Job operations at the Printer.
    "job-uri" (uri):
       The Printer MUST return the Job's URI by returning the contents
       of the REQUIRED "job-uri" Job attribute.
    "job-state" (type1 enum):
       The Printer MUST return the Job's REQUIRED "job-state"
       attribute.  The value of this attribute along with the value of
       the "job-state-reasons" attribute is a "snapshot" of the new
       Job's state when the Printer returns the response.
    "job-state-reasons" (1setOf type2 keyword):
       The Printer MUST return the Job's REQUIRED "job-state-reasons"
       attribute.
    "job-state-message" (text(MAX)):
       The Printer SHOULD return the Job's RECOMMENDED
       "job-state-message" attribute.  If the Printer supports this
       attribute, then it MUST be returned in the response.  If this
       attribute is not returned in the response, the Client can
       assume that the "job-state-message" attribute is not supported
       and will not be returned in a subsequent Job query.
    "number-of-intervening-jobs" (integer(0:MAX)):
       The Printer SHOULD return the Job's RECOMMENDED
       "number-of-intervening-jobs" attribute.  If the Printer
       supports this attribute, then it MUST be returned in the
       response.  If this attribute is not returned in the response,
       the Client can assume that the "number-of-intervening-jobs"
       attribute is not supported and will not be returned in a
       subsequent Job query.

Sweet & McDonald Standards Track [Page 57] RFC 8011 IPP/1.1: Model and Semantics January 2017

 Note: Since any Printer state information that affects a Job's state
 is reflected in the "job-state" and "job-state-reasons" attributes,
 it is sufficient to return only these attributes and no additional
 Printer Status attributes.
 Note: The simplest response consists of just the "attributes-charset"
 and "attributes-natural-language" operation attributes and the
 "job-uri", "job-id", and "job-state" Job attributes.  In this
 simplest case, the status-code is 'successful-ok' and there is no
 "status-message" or "detailed-status-message" operation attribute.

4.2.2. Print-URI Operation

 This OPTIONAL operation is identical to the Print-Job operation
 (Section 4.2.1), except that a Client supplies a URI reference to the
 Document data using the "document-uri" (uri) operation attribute (in
 Group 1) rather than including the Document data itself.  Before
 returning the response, the Printer MUST validate that the Printer
 supports the retrieval method (e.g., 'http', 'ftp', etc.) implied by
 the URI and MUST check for valid URI syntax.  If the Client-supplied
 URI scheme is not supported, i.e., the value is not in the Printer's
 "referenced-uri-scheme-supported" attribute, the Printer MUST reject
 the request and return the 'client-error-uri-scheme-not-supported'
 status-code.
 The Printer MAY validate the accessibility of the Document as part of
 the operation, or subsequently.  If the Printer discovers an
 accessibility problem before returning an operation response, it MUST
 reject the request and return the
 'client-error-document-access-error' status-code.  The Printer MAY
 also return a specific Document access error code using the
 "document-access-error" operation attribute (see Section 4.1.6.4).
 If the Printer discovers this Document accessibility problem after
 accepting the request and returning an operation response with one of
 the successful status-code values, the Printer MUST add the
 "document-access-error" value to the Job's "job-state-reasons"
 attribute and MAY populate the Job's "job-document-access-errors" Job
 Status attribute (see Section 5.3.11).  See the Implementor's Guides
 [RFC3196] [PWG5100.19] for guidance on processing Job Creation
 requests.
 If the Printer supports this operation, it MUST support the
 "reference-uri-schemes-supported" Printer attribute (see
 Section 5.4.27).
 It is up to the Printer to interpret the URI and subsequently "pull"
 the Document data from the source referenced by the URI string.

Sweet & McDonald Standards Track [Page 58] RFC 8011 IPP/1.1: Model and Semantics January 2017

4.2.3. Validate-Job Operation

 This REQUIRED operation is similar to the Print-Job operation
 (Section 4.2.1), except that a Client supplies no Document data and
 the Printer allocates no resources, i.e., it does not create a new
 Job.  This operation is used only to verify the capabilities of a
 Printer against whatever attributes are supplied by the Client in the
 Validate-Job request.  By using the Validate-Job operation, a Client
 can validate that an identical Job Creation request (with the
 Document data) would be accepted.  The Validate-Job operation also
 performs the same security negotiation as the Print-Job, Print-URI,
 and Create-Job operations (see Section 9) so that a Client can check
 that the Client and Printer security requirements can be met before
 performing a Job Creation request.
 The Validate-Job operation does not accept a "document-uri" attribute
 in order to allow a Client to check that the same Print-URI operation
 will be accepted, since the Client doesn't send the data with the
 Print-URI operation.  The Client SHOULD just issue the Print-URI
 request.
 The Printer returns the same status-code values, Operation Attributes
 (Group 1), and Unsupported Attributes (Group 2) as the Print-Job
 operation.  However, no Job Attributes (Group 3) are returned, since
 no Job is created.

4.2.4. Create-Job Operation

 This RECOMMENDED operation is similar to the Print-Job operation
 (Section 4.2.1), except that in the Create-Job request, a Client does
 not supply Document data or any reference to Document data.  Also,
 the Client does not supply any of the "document-name",
 "document-format", "compression", or "document-natural-language"
 operation attributes.  This operation is followed by one or more
 Send-Document or Send-URI operations.  In each of those operation
 requests, the Client MAY supply the "document-name",
 "document-format", and "document-natural-language" attributes for
 each Document in the Job.
 If a Printer supports the Create-Job operation, it MUST also support
 the Send-Document operation.  If the Printer supports the Create-Job
 and Print-URI operations, it MUST also support the Send-URI
 operation.
 If the Printer supports this operation, it MUST support the
 "multiple-operation-time-out" Printer attribute (see Section 5.4.31).

Sweet & McDonald Standards Track [Page 59] RFC 8011 IPP/1.1: Model and Semantics January 2017

 If the Printer supports this operation, then it MUST support the
 "multiple-document-jobs-supported" Printer Description attribute
 (see Section 5.4.16) and indicate whether it supports multiple
 Documents in a Job.
 If the Printer supports this operation and supports multiple
 Documents in a Job, then it MUST support the
 "multiple-document-handling" Job Template attribute with at least
 one value (see Section 5.2.4), and the associated
 "multiple-document-handling-default" and
 "multiple-document-handling-supported" Printer attributes
 (see Section 5.2).
 After the Create-Job operation has completed, the value of the
 "job-state" attribute is similar to the "job-state" after a Print-Job
 operation, even though no Document data has arrived.  A Printer MAY
 set the 'job-data-insufficient' value of the Job's
 "job-state-reasons" attribute to indicate that processing cannot
 begin until sufficient data has arrived and set the "job-state" to
 either 'pending' or 'pending-held'.  A non-spooling Printer that
 doesn't implement the 'pending' Job state can set "job-state" to
 'processing', even though there is not yet any data to process.
 See Sections 5.3.7 and 5.3.8.

4.2.5. Get-Printer-Attributes Operation

 This REQUIRED operation allows a Client to request the values of the
 attributes of a Printer.  In the request, the Client supplies the set
 of Printer attribute names and/or attribute group names in which the
 requester is interested.  In the response, the Printer returns a
 corresponding attribute set with the appropriate attribute values
 filled in.
 For Printers, the possible names of attribute groups are:
 o  'job-template': the subset of the Job Template attributes that
    apply to a Printer (the last two columns of Table 8 in
    Section 5.2) that the implementation supports for Printers.
 o  'printer-description': the subset of the attributes specified in
    Section 5.4 that the implementation supports for Printers.
 o  'all': the special group 'all' that includes all attributes that
    the implementation supports for Printers.
 Since a Client MAY request specific attributes or named groups, there
 is a potential for some overlap.  For example, if a Client requests
 'printer-name' and 'all', the Client is actually requesting the

Sweet & McDonald Standards Track [Page 60] RFC 8011 IPP/1.1: Model and Semantics January 2017

 "printer-name" attribute twice: once by naming it explicitly, and
 once by inclusion in the 'all' group.  In such cases, the Printer
 returns each attribute only once in the response even if it is
 requested multiple times.  The Client SHOULD NOT request the same
 attribute in multiple ways.
 Printers MUST support all group names and MUST return all supported
 attributes belonging to the group.

4.2.5.1. Get-Printer-Attributes Request

 The following sets of attributes are part of the
 Get-Printer-Attributes request:
 Group 1: Operation Attributes
    Natural Language and Character Set:
       The "attributes-charset" and "attributes-natural-language"
       attributes as described in Section 4.1.4.1.
    Target:
       The "printer-uri" (uri) operation attribute, which is the
       target for this operation as described in Section 4.1.5.
    Requesting User Name:
       The "requesting-user-name" (name(MAX)) attribute SHOULD be
       supplied by the Client as described in Section 9.3.
    "requested-attributes" (1setOf keyword):
       The Client MAY supply a set of attribute names and/or attribute
       group names in whose values the requester is interested.  The
       Printer MUST support this attribute.  If the Client omits this
       attribute, the Printer MUST respond as if this attribute had
       been supplied with a value of 'all'.
    "document-format" (mimeMediaType):
       The Client MAY supply and the Printer MUST support this
       attribute.  It is useful for a Client to determine the set of
       supported attribute values that relate to the requested
       Document format.  The Printer MUST return the attributes and
       values that it uses to validate a Job in a Job Creation or
       Validate-Job operation in which this Document format is
       supplied.  The Printer SHOULD return only (1) those attributes

Sweet & McDonald Standards Track [Page 61] RFC 8011 IPP/1.1: Model and Semantics January 2017

       that are supported for the specified format and (2) the
       attribute values that are supported for the specified Document
       format.  By specifying the Document format, the Client can get
       the Printer to eliminate the attributes and values that are not
       supported for a specific Document format.  For example, a
       Printer might have multiple interpreters to support both
       'application/postscript' (for PostScript) and 'text/plain' (for
       text) Documents.  However, only one of those interpreters might
       support the "number-up" Job Template attribute with values of
       '1', '2', and '4'.  The other interpreter might only be able to
       support the "number-up" Job Template attribute with a value of
       '1'.  Thus, a Client can use the Get-Printer-Attributes
       operation to obtain the attributes and values that will be used
       to accept/reject a Job Creation request.
       If the Printer does not distinguish between different sets of
       supported values for each different Document format when
       validating Jobs in the Create-Job, Print-Job, Print-URI, and
       Validate-Job operations, it MUST NOT distinguish between
       different Document formats in the Get-Printer-Attributes
       operation.  If the Printer does distinguish between different
       sets of supported values for each different Document format
       specified by the Client, this specialization applies only to
       the following Printer attributes:
       +  Printer attributes that are Job Template attributes
          ("xxx-default", "xxx-supported", and "xxx-ready")
          (see Table 8 in Section 5.2),
       +  "pdl-override-supported",
       +  "compression-supported",
       +  "job-k-octets-supported",
       +  "job-impressions-supported,
       +  "job-media-sheets-supported",
       +  "printer-driver-installer",
       +  "color-supported", and
       +  "reference-uri-schemes-supported"

Sweet & McDonald Standards Track [Page 62] RFC 8011 IPP/1.1: Model and Semantics January 2017

       The values of all other Printer attributes (including
       "document-format-supported") remain invariant with respect to
       the Client-supplied Document format (except for new Printer
       Description attributes as registered according to Section 7.2).
       If the Client omits this "document-format" operation attribute,
       the Printer MUST respond as if the attribute had been supplied
       with the value of the Printer's "document-format-default"
       attribute.  Clients SHOULD always supply a value for
       "document-format", since the Printer's
       "document-format-default" value can be
       'application/octet-stream', in which case the returned
       attributes and values are for the union of the Document formats
       that the Printer can automatically sense.  For more details,
       see the description of the 'mimeMediaType' attribute syntax in
       Section 5.1.10.
       If the Client supplies a value for the "document-format"
       operation attribute that is not supported by the Printer, i.e.,
       is not among the values of the Printer's
       "document-format-supported" attribute, the Printer MUST reject
       the operation and return the
       'client-error-document-format-not-supported' status-code.

4.2.5.2. Get-Printer-Attributes Response

 The Printer returns the following sets of attributes as part of the
 Get-Printer-Attributes response:
 Group 1: Operation Attributes
    Natural Language and Character Set:
       The "attributes-charset" and "attributes-natural-language"
       attributes as described in Section 4.1.4.2.
    Status Message:
       In addition to the REQUIRED status-code returned in every
       response, the response MAY include a "status-message"
       (text(255)) and/or a "detailed-status-message" (text(MAX))
       operation attribute as described in Appendix B and
       Section 4.1.6.

Sweet & McDonald Standards Track [Page 63] RFC 8011 IPP/1.1: Model and Semantics January 2017

 Group 2: Unsupported Attributes
    See Section 4.1.7 for details on returning unsupported attributes.
    The response MAY contain the "requested-attributes" operation
    attribute with any supplied values (attribute keywords) that were
    requested by the Client but are not supported by the Printer.  If
    the Printer does return unsupported attributes referenced in the
    "requested-attributes" operation attribute and that attribute
    included group names, such as 'all', the unsupported attributes
    MUST NOT include attributes described in this document but not
    supported by the implementation.
 Group 3: Printer Attributes
    This is the set of requested attributes and their current values.
    The Printer ignores (does not respond with) any requested
    attribute that is not supported.  The Printer MAY respond with a
    subset of the supported attributes and values, depending on the
    security policy in force.  However, the Printer MUST respond with
    the 'unknown' value for any supported attribute (including all
    REQUIRED attributes) for which the Printer does not know the
    value.  Also, the Printer MUST respond with 'no-value' for any
    supported attribute (including all REQUIRED attributes) for which
    the Administrator has not configured a value.  See the description
    of the "out-of-band" values in the beginning of Section 5.1.

4.2.6. Get-Jobs Operation

 This REQUIRED operation allows a Client to retrieve the list of Jobs
 belonging to the target Printer.  The Client can also supply a list
 of Job attribute names and/or attribute group names.  A group of Job
 attributes will be returned for each Job that is returned.
 This operation is similar to the Get-Job-Attributes operation, except
 that this Get-Jobs operation returns attributes from possibly more
 than one Job.

Sweet & McDonald Standards Track [Page 64] RFC 8011 IPP/1.1: Model and Semantics January 2017

4.2.6.1. Get-Jobs Request

 The Client submits the Get-Jobs request to a Printer.
 The following groups of attributes are part of the Get-Jobs request:
 Group 1: Operation Attributes
    Natural Language and Character Set:
       The "attributes-charset" and "attributes-natural-language"
       attributes as described in Section 4.1.4.1.
    Target:
       The "printer-uri" (uri) operation attribute, which is the
       target for this operation as described in Section 4.1.5.
    Requesting User Name:
       The "requesting-user-name" (name(MAX)) attribute SHOULD be
       supplied by the Client as described in Section 9.3.
    "limit" (integer(1:MAX)):
       The Client MAY supply and the Printer MUST support this
       attribute.  It is an integer value that determines the maximum
       number of Jobs that a Client will receive from the Printer even
       if "which-jobs" or "my-jobs" (described below) constrain which
       Jobs are returned.  The limit is a "stateless limit" in that if
       the value supplied by the Client is 'N', then only the first
       'N' Jobs are returned in the Get-Jobs response.  If the Client
       does not supply this attribute, the Printer responds with all
       applicable Jobs.
    "requested-attributes" (1setOf type2 keyword):
       The Client MAY supply and the Printer MUST support this
       attribute.  It is a set of Job attribute names and/or attribute
       group names in whose values the requester is interested.  This
       set of attributes is returned for each Job that is returned.
       The allowed attribute group names are the same as those defined
       in the Get-Job-Attributes operation in Section 4.3.4.  If the
       Client does not supply this attribute, the Printer MUST respond
       as if the Client had supplied this attribute with two values:
       "job-uri" and "job-id".

Sweet & McDonald Standards Track [Page 65] RFC 8011 IPP/1.1: Model and Semantics January 2017

    "which-jobs" (type2 keyword):
       The Client MAY supply and the Printer MUST support this
       attribute.  It indicates which Jobs MUST be returned by the
       Printer.  The values for this attribute include:
       +  'completed': Any Job whose state is 'completed', 'canceled',
          or 'aborted'.
       +  'not-completed': Any Job whose state is 'pending',
          'processing', 'processing-stopped', or 'pending-held'.
       A Printer MUST support both values.  However, if the
       implementation does not keep Jobs in the 'completed',
       'canceled', and 'aborted' states, then it returns no Jobs when
       the 'completed' value is supplied.
       If a Client supplies some other value that is not supported by
       the Printer, the Printer MUST copy the attribute and the
       unsupported value to the Unsupported Attributes group, reject
       the request, and return the
       'client-error-attributes-or-values-not-supported' status-code.
       If the Client does not supply this attribute, the Printer MUST
       respond as if the Client had supplied the attribute with a
       value of 'not-completed'.
    "my-jobs" (boolean):
       The Client MAY supply and the Printer MUST support this
       attribute.  It indicates whether Jobs from all users or just
       the Jobs submitted by the requesting user of this request MUST
       be considered as candidate Jobs to be returned by the Printer.
       If the Client does not supply this attribute, the Printer MUST
       respond as if the Client had supplied the attribute with a
       value of 'false', i.e., Jobs from all users.  The means for
       authenticating the requesting user and matching the Jobs is
       described in Section 9.

4.2.6.2. Get-Jobs Response

 The Printer returns all of the Jobs up to the number specified by the
 "limit" attribute that match the criteria as defined by the attribute
 values supplied by the Client in the request.  It is possible that no
 Jobs are returned, since there can literally be no Jobs at the
 Printer or there can be no Jobs that match the criteria supplied by
 the Client.  If the Client requests any Job attributes at all, there
 is a set of Job Attributes returned for each Job.

Sweet & McDonald Standards Track [Page 66] RFC 8011 IPP/1.1: Model and Semantics January 2017

 It is not an error for the Printer to return 0 Jobs.  If the response
 returns 0 Jobs because there are no Jobs matching the criteria, and
 the request would have returned one or more Jobs with a status-code
 of 'successful-ok' if there had been Jobs matching the criteria, then
 the status-code for 0 Jobs MUST be 'successful-ok'.
 Group 1: Operation Attributes
    Natural Language and Character Set:
       The "attributes-charset" and "attributes-natural-language"
       attributes as described in Section 4.1.4.2.
    Status Message:
       In addition to the REQUIRED status-code returned in every
       response, the response MAY include a "status-message"
       (text(255)) and/or a "detailed-status-message" (text(MAX))
       operation attribute as described in Appendix B and
       Section 4.1.6.
 Group 2: Unsupported Attributes
    See Section 4.1.7 for details on returning unsupported attributes.
    The response MAY contain the "requested-attributes" operation
    attribute with any supplied values (attribute keywords) that were
    requested by the Client but are not supported by the Printer.  If
    the Printer does return unsupported attributes referenced in the
    "requested-attributes" operation attribute and that attribute
    included group names, such as 'all', the unsupported attributes
    MUST NOT include attributes described in this document but not
    supported by the implementation.
 Groups 3 to N: Job Attributes
    The Printer responds with one set of Job Attributes for each
    returned Job.  The Printer ignores (does not respond with) any
    requested attribute or value that is not supported or that is
    restricted by the security policy in force, including whether the
    requesting user is the user that submitted the Job
    (Job-originating user) or not (see Section 9).  However, the
    Printer MUST respond with the 'unknown' value for any supported
    attribute (including all REQUIRED attributes) for which the
    Printer does not know the value, unless it would violate the
    security policy.  See the description of the "out-of-band" values
    in the beginning of Section 5.1.

Sweet & McDonald Standards Track [Page 67] RFC 8011 IPP/1.1: Model and Semantics January 2017

    Jobs are returned in the following order:
  • If the Client requests all 'completed' Jobs (Jobs in the

'completed', 'aborted', or 'canceled' states), then the Jobs

       are returned newest to oldest (with respect to actual
       completion time).
  • If the Client requests all 'not-completed' Jobs (Jobs in the

'pending', 'processing', 'pending-held', and

       'processing-stopped' states), then Jobs are returned in
       relative chronological order of expected time to complete
       (based on whatever scheduling algorithm is configured for the
       Printer).

4.2.7. Pause-Printer Operation

 This OPTIONAL operation allows a Client to stop the Printer from
 scheduling Jobs on all its devices.  Depending on implementation, the
 Pause-Printer operation MAY also stop the Printer from processing the
 current Job or Jobs.  Any Job that is currently being printed is
 either (1) stopped as soon as the implementation permits or
 (2) completed, depending on implementation.  The Printer MUST still
 accept Job Creation requests to create new Jobs but MUST prevent any
 Jobs from entering the 'processing' state.
 If the Pause-Printer operation is supported, then the Resume-Printer
 operation MUST be supported, and vice versa.
 The IPP Printer stops the current Job(s) on its device or devices
 that were in the 'processing' or 'processing-stopped' state as soon
 as the implementation permits.  If the implementation will take
 appreciable time to stop, the IPP Printer adds the 'moving-to-paused'
 value to the Printer's "printer-state-reasons" attribute (see
 Section 5.4.12).  When the device or devices have all stopped, the
 IPP Printer transitions the Printer to the 'stopped' state; removes
 the 'moving-to-paused' value, if present; and adds the 'paused' value
 to the Printer's "printer-state-reasons" attribute.
 When the current Job or Jobs complete that were in the 'processing'
 state, the IPP Printer transitions them to the 'completed' state.
 When the current Job or Jobs stop in mid-processing that were in the
 'processing' state, the IPP Printer transitions them to the
 'processing-stopped' state and adds the 'printer-stopped' value to
 the Jobs' "job-state-reasons" attribute.

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 For any Jobs that are 'pending' or 'pending-held', the
 'printer-stopped' value of the Jobs' "job-state-reasons" attribute
 also applies.  However, the IPP Printer MAY update those Jobs'
 "job-state-reasons" values when those Jobs are queried (so-called
 "lazy evaluation").
 The IPP Printer MUST accept the request in any state and transition
 the Printer to the indicated new "printer-state" before returning, as
 shown in Table 2.
 Access Rights: The authenticated user (see Section 9.3) performing
 this operation MUST be an Operator or Administrator of the Printer
 (see Sections 1 and 9.5).  Otherwise, the IPP Printer MUST reject the
 operation and return 'client-error-forbidden',
 'client-error-not-authenticated', or 'client-error-not-authorized'
 as appropriate.

Sweet & McDonald Standards Track [Page 69] RFC 8011 IPP/1.1: Model and Semantics January 2017

 +--------------+--------------+-----------------+-------------------+
 | Current      | New          | "printer-state- | IPP Printer's     |
 | "printer-    | "printer-    | reasons"        | response status-  |
 | state"       | state"       |                 | code and action:  |
 +--------------+--------------+-----------------+-------------------+
 | 'idle'       | 'stopped'    | 'paused'        | 'successful-ok'   |
 +--------------+--------------+-----------------+-------------------+
 | 'processing' | 'processing' | 'moving-to-     | Option 1:         |
 |              |              | paused'         | 'successful-ok';  |
 |              |              |                 | Later, when all   |
 |              |              |                 | output has        |
 |              |              |                 | stopped, the      |
 |              |              |                 | "printer-state"   |
 |              |              |                 | becomes           |
 |              |              |                 | 'stopped', and    |
 |              |              |                 | the 'paused'      |
 |              |              |                 | value replaces    |
 |              |              |                 | the 'moving-to-   |
 |              |              |                 | paused' value in  |
 |              |              |                 | the "printer-     |
 |              |              |                 | state-reasons"    |
 |              |              |                 | attribute         |
 +--------------+--------------+-----------------+-------------------+
 | 'processing' | 'stopped'    | 'paused'        | Option 2:         |
 |              |              |                 | 'successful-ok';  |
 |              |              |                 | all device output |
 |              |              |                 | stopped           |
 |              |              |                 | immediately       |
 +--------------+--------------+-----------------+-------------------+
 | 'stopped'    | 'stopped'    | 'paused'        | 'successful-ok'   |
 +--------------+--------------+-----------------+-------------------+
               Table 2: Pause-Printer State Transitions

Sweet & McDonald Standards Track [Page 70] RFC 8011 IPP/1.1: Model and Semantics January 2017

4.2.7.1. Pause-Printer Request

 The following groups of attributes are part of the Pause-Printer
 request:
 Group 1: Operation Attributes
    Natural Language and Character Set:
       The "attributes-charset" and "attributes-natural-language"
       attributes as described in Section 4.1.4.1.
    Target:
       The "printer-uri" (uri) operation attribute, which is the
       target for this operation as described in Section 4.1.5.
    Requesting User Name:
       The "requesting-user-name" (name(MAX)) attribute SHOULD be
       supplied by the Client as described in Section 9.3.

4.2.7.2. Pause-Printer Response

 The following groups of attributes are part of the Pause-Printer
 response:
 Group 1: Operation Attributes
    Natural Language and Character Set:
       The "attributes-charset" and "attributes-natural-language"
       attributes as described in Section 4.1.4.2.
    Status Message:
       In addition to the REQUIRED status-code returned in every
       response, the response MAY include a "status-message"
       (text(255)) and/or a "detailed-status-message" (text(MAX))
       operation attribute as described in Appendix B and
       Section 4.1.6.
 Group 2: Unsupported Attributes
    See Section 4.1.7 for details on returning unsupported attributes.

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4.2.8. Resume-Printer Operation

 This OPTIONAL operation allows a Client to resume the Printer
 scheduling Jobs on all its devices.  The Printer MUST remove the
 'paused' and 'moving-to-paused' values from the Printer's
 "printer-state-reasons" attribute, if present.  If there are no other
 reasons to keep a device paused (such as a media jam), the IPP
 Printer is free to transition itself to the 'processing' or 'idle'
 state, depending on whether there are Jobs to be processed or not,
 respectively, and the device(s) resumes processing Jobs.
 If the Pause-Printer operation is supported, then the Resume-Printer
 operation MUST be supported, and vice versa.
 The IPP Printer removes the 'printer-stopped' value from any Job's
 "job-state-reasons" attributes contained in that Printer.
 The IPP Printer MUST accept the request in any state and transition
 the Printer to the indicated new state as shown in Table 3.
 Access Rights: The authenticated user (see Section 9.3) performing
 this operation MUST be an Operator or Administrator of the Printer
 (see Sections 1 and 9.5).  Otherwise, the IPP Printer MUST reject the
 operation and return 'client-error-forbidden',
 'client-error-not-authenticated', or 'client-error-not-authorized'
 as appropriate.
 The Resume-Printer request and Resume-Printer response have the same
 attribute groups and attributes as the Pause-Printer operation (see
 Sections 4.2.7.1 and 4.2.7.2).
 +-----------------+-----------------+-------------------------------+
 | Current         | New "printer-   | IPP Printer's response        |
 | "printer-state" | state"          | status-code and action:       |
 +-----------------+-----------------+-------------------------------+
 | 'idle'          | 'idle'          | 'successful-ok'               |
 +-----------------+-----------------+-------------------------------+
 | 'processing'    | 'processing'    | 'successful-ok'               |
 +-----------------+-----------------+-------------------------------+
 | 'stopped'       | 'processing'    | 'successful-ok', when there   |
 |                 |                 | are Jobs to be processed      |
 +-----------------+-----------------+-------------------------------+
 | 'stopped'       | 'idle'          | 'successful-ok', when there   |
 |                 |                 | are no Jobs to be processed   |
 +-----------------+-----------------+-------------------------------+
               Table 3: Resume-Printer State Transitions

Sweet & McDonald Standards Track [Page 72] RFC 8011 IPP/1.1: Model and Semantics January 2017

4.2.9. Purge-Jobs Operation

 This DEPRECATED operation allows a Client to remove all Jobs from a
 Printer, regardless of their Job states, including Jobs in the
 Printer's Job History (see Section 5.3.7.2).  After a Purge-Jobs
 operation has been performed, a Printer MUST return no Jobs in
 subsequent Get-Job-Attributes and Get-Jobs responses (until new Jobs
 are submitted).
 Note: This operation SHOULD NOT be supported in new implementations,
 since it destroys Printer accounting information.
 Whether the Purge-Jobs (and Get-Jobs) operation affects Jobs that
 were submitted to the device from sources other than the IPP Printer
 in the same way that the Purge-Jobs operation affects Jobs that were
 submitted to the IPP Printer using IPP depends on implementation,
 i.e., on whether IPP is being used as a universal management protocol
 or just to manage IPP Jobs, respectively.
 Note: If an Operator wants to cancel all Jobs without clearing out
 the Job History, the Operator uses the Cancel-Job operation on each
 Job instead of using the Purge-Jobs operation.
 If this OPTIONAL operation is supported, the Printer MUST accept this
 operation in any state and transition the Printer to the 'idle'
 state.
 Access Rights: The authenticated user (see Section 9.3) performing
 this operation MUST be an Operator or Administrator of the Printer
 (see Sections 1 and 9.5).  Otherwise, the Printer MUST reject the
 operation and return 'client-error-forbidden',
 'client-error-not-authenticated', and 'client-error-not-authorized'
 as appropriate.
 The Purge-Jobs request and Purge-Jobs response have the same
 attribute groups and attributes as the Pause-Printer operation (see
 Sections 4.2.7.1 and 4.2.7.2).

4.3. Job Operations

 All Job operations are directed at Jobs.  A Client MUST always supply
 some means of identifying the Job object in order to identify the
 correct target of the operation.  That Job identification SHOULD be
 the combination of a Printer URI with a Job ID but MAY be the
 (single) Job URI.  The IPP implementation MUST support both forms of
 identification for every Job.

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4.3.1. Send-Document Operation

 This RECOMMENDED operation allows a Client to add a Document to a Job
 that was created using the Create-Job operation.  In the Create-Job
 response, the Printer returns the Job's URI (the "job-uri" attribute)
 and the Job's 32-bit identifier (the "job-id" attribute).  For each
 new Document that the Client desires to add, the Client uses a
 Send-Document operation.  Each Send-Document request contains the
 entire stream of Document data for one Document.
 If the Printer supports this operation but does not support multiple
 Documents per Job, the Printer MUST reject subsequent Send-Document
 operations supplied with data and return the
 'server-error-multiple-document-jobs-not-supported' status-code.
 However, the Printer MUST accept the first Document with a 'true' or
 'false' value for the "last-document" operation attribute (see
 below), so that Clients MAY always submit one Document Job with a
 'false' value for "last-document" in the first Send-Document and a
 'true' value for "last-document" in the second Send-Document (with
 no data).
 Since the Create-Job and the send operations (Send-Document or
 Send-URI operations) that follow could occur over an arbitrarily long
 period of time for a particular Job, a Client MUST send another send
 operation within a minimum time interval, as defined by the IPP
 Printer, after the receipt of the previous request for the Job.  If a
 Printer supports the Create-Job and Send-Document operations, the
 Printer MUST support the "multiple-operation-time-out" attribute (see
 Section 5.4.31).  This attribute indicates the minimum number of
 seconds the Printer will wait for the next send operation before
 taking some recovery action.
 A Printer MUST recover from an errant Client that does not supply a
 send operation, sometime after the minimum time interval specified by
 the Printer's "multiple-operation-time-out" attribute.  Such recovery
 MAY include any of the following actions or other recovery actions:
 1.  Assume that the Job is an invalid Job, start the process of
     changing the Job state to 'aborted', add the 'aborted-by-system'
     value to the Job's "job-state-reasons" attribute (see
     Section 5.3.8), and clean up all resources associated with the
     Job.  In this case, if another send operation is finally
     received, the Printer responds with a 'client-error-not-possible'
     or 'client-error-not-found' status-code, depending on whether the
     Job is still around when the send operation finally arrives.

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 2.  Assume that the last send operation received was in fact the last
     Document (as if the "last-document" flag had been set to 'true'),
     close the Job, and proceed to process it (i.e., move the Job's
     state to 'pending').
 3.  Assume that the last send operation received was in fact the last
     Document and close the Job, but move it to the 'pending-held'
     state and add the 'submission-interrupted' value to the Job's
     "job-state-reasons" attribute (see Section 5.3.8).  This action
     allows the user or an Operator to determine whether to continue
     processing the Job by moving it back to the 'pending' state using
     the Release-Job operation (see Section 4.3.6) or to cancel the
     Job using the Cancel-Job operation (see Section 4.3.3).
 Each implementation is free to decide the "best" action to take,
 depending on the following: local policy, whether any Documents have
 been added, whether the implementation spools Jobs or not, and/or any
 other piece of information available to it.  If the choice is to
 abort the Job, it is possible that the Job has already been processed
 to the point that some Media Sheet pages have been printed.
 Access Rights: The authenticated user (see Section 9.3) performing
 this operation must be either the Job owner (as determined in the
 Create-Job operation) or an Operator or Administrator of the Printer
 (see Sections 1 and 9.5).  Otherwise, the Printer MUST reject the
 operation and return 'client-error-forbidden',
 'client-error-not-authenticated', or 'client-error-not-authorized'
 as appropriate.

4.3.1.1. Send-Document Request

 The following attribute sets are part of the Send-Document request:
 Group 1: Operation Attributes
    Natural Language and Character Set:
       The "attributes-charset" and "attributes-natural-language"
       attributes as described in Section 4.1.4.1.
    Target:
       Either the "printer-uri" (uri) plus "job-id" (integer(1:MAX)),
       or the "job-uri" (uri) operation attribute(s), which define the
       target for this operation as described in Section 4.1.5.

Sweet & McDonald Standards Track [Page 75] RFC 8011 IPP/1.1: Model and Semantics January 2017

    Requesting User Name:
       The "requesting-user-name" (name(MAX)) attribute SHOULD be
       supplied by the Client as described in Section 9.3.
    "document-name" (name(MAX)):
       The Client MAY supply and the Printer MUST support this
       attribute.  It contains the Client-supplied Document name.  The
       Document name MAY be different than the Job name and is not
       guaranteed to be unique across multiple Documents in the same
       Job.  Typically, the Client software automatically supplies the
       Document name on behalf of the End User by using a file name or
       an application-generated name.  See the description of the
       "document-name" operation attribute in the Print-Job request
       (Section 4.2.1.1) for more information about this attribute.
    "compression" (type2 keyword):
       See the description of "compression" for the Print-Job
       operation in Section 4.2.1.1.
    "document-format" (mimeMediaType):
       See the description of "document-format" for the Print-Job
       operation in Section 4.2.1.1.
    "document-natural-language" (naturalLanguage):
       The Client MAY supply and the Printer MAY support this
       attribute.  It specifies the natural language of the Document
       content for those Document formats that require a specification
       of the natural language in order to properly image the
       Document.
    "last-document" (boolean):
       The Client MUST supply and the Printer MUST support this
       attribute.  It is a boolean flag that is set to 'true' if this
       is the last Document for the Job; otherwise, it is set to
       'false'.

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 Group 2: Document Data
    The Client MUST supply the Document data if the "last-document"
    flag is set to 'false'.  However, since a Client might not know
    that the previous Document sent with a Send-Document (or Send-URI)
    operation was the last Document (i.e., the "last-document"
    attribute was set to 'false'), it is legal to send a Send-Document
    request with no Document data where the "last-document" flag is
    set to 'true'.  Such a request MUST NOT increment the value of the
    Job's "number-of-documents" attribute, since no real Document was
    added to the Job.  It is not an error for a Client to submit a Job
    with no actual Document data, i.e., only a single Create-Job and
    Send-Document request with a "last-document" operation attribute
    set to 'true' with no Document data.

4.3.1.2. Send-Document Response

 The following sets of attributes are part of the Send-Document
 response:
 Group 1: Operation Attributes
    Natural Language and Character Set:
       The "attributes-charset" and "attributes-natural-language"
       attributes as described in Section 4.1.4.2.
    Status Message:
       In addition to the REQUIRED status-code returned in every
       response, the response MAY include a "status-message"
       (text(255)) and/or a "detailed-status-message" (text(MAX))
       operation attribute as described in Appendix B and
       Section 4.1.6.
 Group 2: Unsupported Attributes
    See Section 4.1.7 for details on returning unsupported attributes.
 Group 3: Job Object Attributes
    This is the same set of attributes as those described in the
    Print-Job response (see Section 4.2.1.2).

Sweet & McDonald Standards Track [Page 77] RFC 8011 IPP/1.1: Model and Semantics January 2017

4.3.2. Send-URI Operation

 This RECOMMENDED operation is identical to the Send-Document
 operation (see Section 4.3.1), except that a Client MUST supply a URI
 reference ("document-uri" operation attribute) rather than the
 Document data itself.  If a Printer supports this operation, Clients
 can use both Send-URI and Send-Document operations to add new
 Documents to an existing Job.  However, if a Client needs to indicate
 that the previous Send-URI or Send-Document was the last Document,
 the Client MUST use the Send-Document operation with no Document data
 and the "last-document" flag set to 'true' (rather than using a
 Send-URI operation with no "document-uri" operation attribute).
 If a Printer supports this operation, it MUST also support the
 Print-URI operation (see Section 4.2.2).
 The Printer MUST validate the syntax and URI scheme of the supplied
 URI before returning a response, just as in the Print-URI operation.
 The Printer MAY validate the accessibility of the Document as part of
 the operation, or subsequently (see Section 4.2.2).

4.3.3. Cancel-Job Operation

 This REQUIRED operation allows a Client to cancel a Print Job from
 the time the Job is created up to the time it is completed, canceled,
 or aborted.  Since a Job might already be printing by the time a
 Cancel-Job is received, some Media Sheet pages might be printed
 before the Job is actually terminated.
 The Printer MUST accept or reject the request based on the Job's
 current state and transition the Job to the indicated new state as
 shown in Table 4.
 Access Rights: The authenticated user (see Section 9.3) performing
 this operation must be either the Job owner or an Operator or
 Administrator of the Printer (see Sections 1 and 9.5).  Otherwise,
 the Printer MUST reject the operation and return
 'client-error-forbidden', 'client-error-not-authenticated', or
 'client-error-not-authorized' as appropriate.

Sweet & McDonald Standards Track [Page 78] RFC 8011 IPP/1.1: Model and Semantics January 2017

 +-------------------+--------------------+--------------------------+
 | Current "job-     | New "job-state"    | Printer's response       |
 | state"            |                    | status-code and action:  |
 +-------------------+--------------------+--------------------------+
 | 'pending'         | 'canceled'         | 'successful-ok'          |
 +-------------------+--------------------+--------------------------+
 | 'pending-held'    | 'canceled'         | 'successful-ok'          |
 +-------------------+--------------------+--------------------------+
 | 'processing'      | 'canceled'         | 'successful-ok'          |
 +-------------------+--------------------+--------------------------+
 | 'processing'      | 'processing'       | 'successful-ok' (note 1) |
 +-------------------+--------------------+--------------------------+
 | 'processing'      | 'processing'       | 'client-error-not-       |
 |                   |                    | possible' (note 2)       |
 +-------------------+--------------------+--------------------------+
 | 'processing-      | 'canceled'         | 'successful-ok'          |
 | stopped'          |                    |                          |
 +-------------------+--------------------+--------------------------+
 | 'processing-      | 'processing-       | 'successful-ok' (note 1) |
 | stopped'          | stopped'           |                          |
 +-------------------+--------------------+--------------------------+
 | 'processing-      | 'processing-       | 'client-error-not-       |
 | stopped'          | stopped'           | possible' (note 2)       |
 +-------------------+--------------------+--------------------------+
 | 'completed'       | 'completed'        | 'client-error-not-       |
 |                   |                    | possible'                |
 +-------------------+--------------------+--------------------------+
 | 'canceled'        | 'canceled'         | 'client-error-not-       |
 |                   |                    | possible'                |
 +-------------------+--------------------+--------------------------+
 | 'aborted'         | 'aborted'          | 'client-error-not-       |
 |                   |                    | possible'                |
 +-------------------+--------------------+--------------------------+
                 Table 4: Cancel-Job State Transitions
 Note 1: If the implementation requires some measurable time to cancel
 the Job in the 'processing' or 'processing-stopped' Job state, the
 Printer MUST add the 'processing-to-stop-point' value to the Job's
 "job-state-reasons" attribute and then transition the Job to the
 'canceled' state when the processing ceases (see Section 5.3.8).
 Note 2: If the Job already has the 'processing-to-stop-point' value
 in its "job-state-reasons" attribute, then the Printer MUST reject a
 Cancel-Job operation.

Sweet & McDonald Standards Track [Page 79] RFC 8011 IPP/1.1: Model and Semantics January 2017

4.3.3.1. Cancel-Job Request

 The following groups of attributes are part of the Cancel-Job
 request:
 Group 1: Operation Attributes
    Natural Language and Character Set:
       The "attributes-charset" and "attributes-natural-language"
       attributes as described in Section 4.1.4.1.
    Target:
       Either the "printer-uri" (uri) plus "job-id" (integer(1:MAX)),
       or the "job-uri" (uri) operation attribute(s), which define the
       target for this operation as described in Section 4.1.5.
    Requesting User Name:
       The "requesting-user-name" (name(MAX)) attribute SHOULD be
       supplied by the Client as described in Section 9.3.
    "message" (text(127)):
       The Client MAY supply and the Printer MAY support this
       attribute.  It is a message to the Operator.  This "message"
       attribute is not the same as the "job-message-from-operator"
       attribute.  That attribute is used to report a message from the
       Operator to the End User that queries that attribute.  This
       "message" operation attribute is used to send a message from
       the Client to the Operator along with the operation request.
       How or where to display this message to the Operator (if
       at all) is an implementation decision.

Sweet & McDonald Standards Track [Page 80] RFC 8011 IPP/1.1: Model and Semantics January 2017

4.3.3.2. Cancel-Job Response

 The following sets of attributes are part of the Cancel-Job response:
 Group 1: Operation Attributes
    Natural Language and Character Set:
       The "attributes-charset" and "attributes-natural-language"
       attributes as described in Section 4.1.4.2.
    Status Message:
       In addition to the REQUIRED status-code returned in every
       response, the response MAY include a "status-message"
       (text(255)) and/or a "detailed-status-message" (text(MAX))
       operation attribute as described in Appendix B and
       Section 4.1.6.
 Group 2: Unsupported Attributes
    See Section 4.1.7 for details on returning unsupported attributes.
    Once a successful response has been sent, the implementation
    guarantees that the Job will eventually end up in the 'canceled'
    state.  Between the time that the Cancel-Job operation is accepted
    and when the Job enters the 'canceled' job-state (see
    Section 5.3.7), the "job-state-reasons" attribute SHOULD contain
    the 'processing-to-stop-point' value, which indicates to later
    queries that although the Job might still be 'processing' it will
    eventually end up in the 'canceled' state, not the 'completed'
    state.

4.3.4. Get-Job-Attributes Operation

 This REQUIRED operation allows a Client to request the values of
 attributes of a Job, and it is almost identical to the
 Get-Printer-Attributes operation (see Section 4.2.5).  The only
 differences are that the operation is directed at a Job rather than a
 Printer, there is no "document-format" operation attribute used when
 querying a Job, and the returned attribute group is a set of Job
 attributes rather than a set of Printer attributes.

Sweet & McDonald Standards Track [Page 81] RFC 8011 IPP/1.1: Model and Semantics January 2017

 For Jobs, the possible names of attribute groups are:
 o  'job-template': the subset of the Job Template attributes that
    apply to a Job (the first column of Table 8 in Section 5.2) that
    the implementation supports for Jobs.
 o  'job-description': the subset of the Job Description and Status
    attributes specified in Section 5.3 that the implementation
    supports for Jobs.
 o  'all': the special group 'all' that includes all attributes that
    the implementation supports for Jobs.
 Since a Client MAY request specific attributes or named groups, there
 is a potential for some overlap.  For example, if a Client requests
 'job-name' and 'job-description', the Client is actually requesting
 the "job-name" attribute once by naming it explicitly, and once by
 inclusion in the 'job-description' group.  In such cases, the Printer
 returns the attribute only once in the response even if it is
 requested multiple times.  The Client SHOULD NOT request the same
 attribute in multiple ways.
 Jobs MUST support all group names and MUST return all supported
 attributes belonging to the group.

4.3.4.1. Get-Job-Attributes Request

 The following groups of attributes are part of the Get-Job-Attributes
 request when the request is directed at a Job:
 Group 1: Operation Attributes
    Natural Language and Character Set:
       The "attributes-charset" and "attributes-natural-language"
       attributes as described in Section 4.1.4.1.
    Target:
       Either the "printer-uri" (uri) plus "job-id" (integer(1:MAX)),
       or the "job-uri" (uri) operation attribute(s), which define the
       target for this operation as described in Section 4.1.5.
    Requesting User Name:
       The "requesting-user-name" (name(MAX)) attribute SHOULD be
       supplied by the Client as described in Section 9.3.

Sweet & McDonald Standards Track [Page 82] RFC 8011 IPP/1.1: Model and Semantics January 2017

    "requested-attributes" (1setOf keyword):
       The Client MAY supply and the Printer MUST support this
       attribute.  It is a set of attribute names and/or attribute
       group names in whose values the requester is interested.  If
       the Client omits this attribute, the Printer MUST respond as if
       this attribute had been supplied with a value of 'all'.

4.3.4.2. Get-Job-Attributes Response

 The Printer returns the following sets of attributes as part of the
 Get-Job-Attributes response:
 Group 1: Operation Attributes
    Natural Language and Character Set:
       The "attributes-charset" and "attributes-natural-language"
       attributes as described in Section 4.1.4.2.
       "attributes-natural-language" MAY be the natural language of
       the Job, rather than the one requested.
    Status Message:
       In addition to the REQUIRED status-code returned in every
       response, the response MAY include a "status-message"
       (text(255)) and/or a "detailed-status-message" (text(MAX))
       operation attribute as described in Appendix B and
       Section 4.1.6.
 Group 2: Unsupported Attributes
    See Section 4.1.7 for details on returning unsupported attributes.
    The response MAY contain the "requested-attributes" operation
    attribute with any supplied values (attribute keywords) that were
    requested by the Client but are not supported by the Printer.  If
    the Printer does return unsupported attributes referenced in the
    "requested-attributes" operation attribute and that attribute
    included group names, such as 'all', the unsupported attributes
    MUST NOT include attributes described in this document but not
    supported by the implementation.

Sweet & McDonald Standards Track [Page 83] RFC 8011 IPP/1.1: Model and Semantics January 2017

 Group 3: Job Attributes
    This is the set of requested attributes and their current values.
    The Printer ignores (does not respond with) any requested
    attribute or value that is not supported or that is restricted by
    the security policy in force, including whether the requesting
    user is the user that submitted the Job (Job-originating user) or
    not (see Section 9).  However, the Printer MUST respond with the
    'unknown' value for any supported attribute (including all
    REQUIRED attributes) for which the Printer does not know the
    value, unless it would violate the security policy.  See the
    description of the "out-of-band" values in the beginning of
    Section 5.1.

4.3.5. Hold-Job Operation

 This OPTIONAL operation allows a Client to hold a pending Job in the
 queue so that it is not eligible for scheduling.  If the Hold-Job
 operation is supported, then the Release-Job operation MUST be
 supported, and vice versa.  The OPTIONAL "job-hold-until" operation
 attribute allows a Client to specify whether to hold the Job
 indefinitely or until a specified time period, if supported.
 The Printer MUST accept or reject the request based on the Job's
 current state and transition the Job to the indicated new state as
 shown in Table 5.
 Note: In order to keep the Hold-Job operation simple, such a request
 is rejected when the Job is in the 'processing' or
 'processing-stopped' state.  If an operation is needed to hold Jobs
 while in either of these states, it will be added as an additional
 operation, rather than overloading the Hold-Job operation.  Then it
 is clear to Clients by querying the Printer's "operations-supported"
 (see Section 5.4.15) and the Job's "job-state" (see Section 5.3.7)
 attributes which operations are possible.
 Access Rights: The authenticated user (see Section 9.3) performing
 this operation must be either the Job owner or an Operator or
 Administrator of the Printer (see Sections 1 and 9.5).  Otherwise,
 the Printer MUST reject the operation and return
 'client-error-forbidden', 'client-error-not-authenticated', or
 'client-error-not-authorized' as appropriate.

Sweet & McDonald Standards Track [Page 84] RFC 8011 IPP/1.1: Model and Semantics January 2017

 +-------------------+--------------------+--------------------------+
 | Current "job-     | New "job-state"    | Printer's response       |
 | state"            |                    | status-code and action:  |
 +-------------------+--------------------+--------------------------+
 | 'pending'         | 'pending-held'     | 'successful-ok' (note 1) |
 +-------------------+--------------------+--------------------------+
 | 'pending'         | 'pending'          | 'successful-ok' (note 2) |
 +-------------------+--------------------+--------------------------+
 | 'pending-held'    | 'pending-held'     | 'successful-ok' (note 1) |
 +-------------------+--------------------+--------------------------+
 | 'pending-held'    | 'pending'          | 'successful-ok' (note 2) |
 +-------------------+--------------------+--------------------------+
 | 'processing'      | 'processing'       | 'client-error-not-       |
 |                   |                    | possible'                |
 +-------------------+--------------------+--------------------------+
 | 'processing-      | 'processing-       | 'client-error-not-       |
 | stopped'          | stopped'           | possible'                |
 +-------------------+--------------------+--------------------------+
 | 'completed'       | 'completed'        | 'client-error-not-       |
 |                   |                    | possible'                |
 +-------------------+--------------------+--------------------------+
 | 'canceled'        | 'canceled'         | 'client-error-not-       |
 |                   |                    | possible'                |
 +-------------------+--------------------+--------------------------+
 | 'aborted'         | 'aborted'          | 'client-error-not-       |
 |                   |                    | possible'                |
 +-------------------+--------------------+--------------------------+
                  Table 5: Hold-Job State Transitions
 Note 1: If the implementation supports multiple reasons for a Job to
 be in the 'pending-held' state, the Printer MUST add the
 "job-hold-until-specified" value to the Job's "job-state-reasons"
 attribute.
 Note 2: If the Printer supports the "job-hold-until" operation
 attribute, but the specified time period has already started (or is
 the 'no-hold' value) and there are no other reasons to hold the Job,
 the Printer MUST make the Job be a candidate for processing
 immediately (see Section 5.2.2) by putting the Job in the 'pending'
 state.

Sweet & McDonald Standards Track [Page 85] RFC 8011 IPP/1.1: Model and Semantics January 2017

4.3.5.1. Hold-Job Request

 The groups and operation attributes are the same as those defined for
 a Cancel-Job request (see Section 4.3.3.1), with the addition of the
 following Group 1 operation attribute:
    "job-hold-until" (type2 keyword | name(MAX)):
    The Client MAY supply and the Printer MUST support this operation
    attribute in a Hold-Job request if it supports the
    "job-hold-until" Job Template attribute in Job Creation requests.
    See Section 5.2.2.  The Printer SHOULD support the
    "job-hold-until" Job Template attribute for use in Job Creation
    requests with at least the 'indefinite' value, if it supports the
    Hold-Job operation.  Otherwise, a Client cannot create a Job and
    hold it immediately (without picking some supported time period in
    the future).
    If supplied and supported as specified in the Printer's
    "job-hold-until-supported" attribute, the Printer copies the
    supplied operation attribute to the Job, replacing the Job's
    previous "job-hold-until" attribute, if present, and makes the Job
    a candidate for scheduling during the supplied named time period.
    If supplied but either the "job-hold-until" operation attribute
    itself or the value supplied is not supported, the Printer accepts
    the request, returns the unsupported attribute or value in the
    Unsupported Attributes group according to Section 4.1.7, returns
    the 'successful-ok-ignored-or-substituted-attributes' status-code,
    and holds the Job indefinitely until a Client performs a
    subsequent Release-Job operation.
    If (1) the Client supplies either a value that specifies a time
    period that has already started or the 'no-hold' value (meaning
    don't hold the Job) and (2) the Printer supports the
    "job-hold-until" operation attribute and there are no other
    reasons to hold the Job, the Printer MUST accept the operation and
    make the Job be a candidate for processing immediately (see
    Section 5.2.2).
    If the Client does not supply a "job-hold-until" operation
    attribute in the request, the Printer MUST populate the Job with a
    "job-hold-until" attribute with the 'indefinite' value (if the
    Printer supports the "job-hold-until" attribute) and hold the Job
    indefinitely, until a Client performs a Release-Job operation.

Sweet & McDonald Standards Track [Page 86] RFC 8011 IPP/1.1: Model and Semantics January 2017

4.3.5.2. Hold-Job Response

 The groups and attributes are the same as those defined for a
 Cancel-Job response (see Section 4.3.3.2).

4.3.6. Release-Job Operation

 This OPTIONAL operation allows a Client to release a previously held
 Job so that it is again eligible for scheduling.  If the Hold-Job
 operation is supported, then the Release-Job operation MUST be
 supported, and vice versa.
 This operation removes the "job-hold-until" Job attribute, if
 present, from the Job that had been supplied in the Create-Job or
 most recent Hold-Job or Restart-Job operation and removes its effect
 on the Job.  The Printer MUST remove the "job-hold-until-specified"
 value from the Job's "job-state-reasons" attribute, if present.  See
 Section 5.3.8.
 The Printer MUST accept or reject the request based on the Job's
 current state and transition the Job to the indicated new state as
 shown in Table 6.
 Access Rights: The authenticated user (see Section 9.3) performing
 this operation must be either the Job owner or an Operator or
 Administrator of the Printer (see Sections 1 and 9.5).  Otherwise,
 the Printer MUST reject the operation and return
 'client-error-forbidden', 'client-error-not-authenticated', or
 'client-error-not-authorized' as appropriate.
 The Release-Job request and Release-Job response have the same
 attribute groups and attributes as the Cancel-Job operation (see
 Sections 4.3.3.1 and 4.3.3.2).

Sweet & McDonald Standards Track [Page 87] RFC 8011 IPP/1.1: Model and Semantics January 2017

 +-------------------+--------------------+--------------------------+
 | Current "job-     | New "job-state"    | Printer's response       |
 | state"            |                    | status-code and action:  |
 +-------------------+--------------------+--------------------------+
 | 'pending'         | 'pending'          | 'successful-ok'.  No     |
 |                   |                    | effect on the Job.       |
 +-------------------+--------------------+--------------------------+
 | 'pending-held'    | 'pending-held'     | 'successful-ok' (note 1) |
 +-------------------+--------------------+--------------------------+
 | 'pending-held'    | 'pending'          | 'successful-ok'          |
 +-------------------+--------------------+--------------------------+
 | 'processing'      | 'processing'       | 'successful-ok'.  No     |
 |                   |                    | effect on the Job.       |
 +-------------------+--------------------+--------------------------+
 | 'processing-      | 'processing-       | 'successful-ok'.  No     |
 | stopped'          | stopped'           | effect on the Job.       |
 +-------------------+--------------------+--------------------------+
 | 'completed'       | 'completed'        | 'client-error-not-       |
 |                   |                    | possible'                |
 +-------------------+--------------------+--------------------------+
 | 'canceled'        | 'canceled'         | 'client-error-not-       |
 |                   |                    | possible'                |
 +-------------------+--------------------+--------------------------+
 | 'aborted'         | 'aborted'          | 'client-error-not-       |
 |                   |                    | possible'                |
 +-------------------+--------------------+--------------------------+
                Table 6: Release-Job State Transitions
 Note 1: If there are other reasons to keep the Job in the
 'pending-held' state, such as 'resources-are-not-ready', the Job
 remains in the 'pending-held' state.  Thus, the 'pending-held' state
 is not just for Jobs that have the "job-hold-until" attribute applied
 to them but is also used for any reason that will keep the Job from
 being a candidate for scheduling and processing, such as
 'resources-are-not-ready'.  See the "job-hold-until" attribute
 (Section 5.2.2).

Sweet & McDonald Standards Track [Page 88] RFC 8011 IPP/1.1: Model and Semantics January 2017

4.3.7. Restart-Job Operation

 This DEPRECATED operation allows a Client to restart a Job that is
 retained in the queue after processing has completed (see
 Section 5.3.7.2).
 Note: This operation SHOULD NOT be supported in new implementations,
 since it destroys Printer accounting information.  The Resubmit-Job
 operation [PWG5100.11] is the safe replacement for this operation and
 makes a copy of the Job, assigns a new "job-uri" and "job-id" to the
 copy, and resets the Job progress attributes in the new copy only.
 The Restart-Job operation moves the Job to the 'pending' or
 'pending-held' Job state and restarts at the beginning on the same
 Printer with the same attribute values.  If any of the Documents in
 the Job were passed by reference (Print-URI or Send-URI), the Printer
 MUST refetch the data, since the semantics of Restart-Job are to
 repeat all Job processing.  The Job Status attributes that accumulate
 Job progress, such as "job-impressions-completed",
 "job-media-sheets-completed", and "job-k-octets-processed", MUST be
 reset to 0 so that they give an accurate record of the Job from its
 restart point.  The Job MUST continue to use the same "job-uri" and
 "job-id" attribute values.
 The Printer MUST accept or reject the request based on the Job's
 current state and transition the Job to the indicated new state as
 shown in Table 7.
 Note: In order to prevent a user from inadvertently restarting a Job
 in the middle, the Restart-Job request is rejected when the Job is in
 the 'processing' or 'processing-stopped' state.  If in the future an
 operation is needed to hold or restart Jobs while in either of these
 states, it will be added as an additional operation, rather than
 overloading the Restart-Job operation, so that it is clear that the
 user intended that the current Job not be completed.
 Access Rights: The authenticated user (see Section 9.3) performing
 this operation must be either the Job owner or an Operator or
 Administrator of the Printer (see Sections 1 and 9.5).  Otherwise,
 the Printer MUST reject the operation and return
 'client-error-forbidden', 'client-error-not-authenticated', or
 'client-error-not-authorized' as appropriate.

Sweet & McDonald Standards Track [Page 89] RFC 8011 IPP/1.1: Model and Semantics January 2017

 +-------------------+--------------------+--------------------------+
 | Current "job-     | New "job-state"    | Printer's response       |
 | state"            |                    | status-code and action:  |
 +-------------------+--------------------+--------------------------+
 | 'pending'         | 'pending'          | 'client-error-not-       |
 |                   |                    | possible'                |
 +-------------------+--------------------+--------------------------+
 | 'pending-held'    | 'pending-held'     | 'client-error-not-       |
 |                   |                    | possible'                |
 +-------------------+--------------------+--------------------------+
 | 'processing'      | 'processing'       | 'client-error-not-       |
 |                   |                    | possible'                |
 +-------------------+--------------------+--------------------------+
 | 'processing-      | 'processing-       | 'client-error-not-       |
 | stopped'          | stopped'           | possible'                |
 +-------------------+--------------------+--------------------------+
 | 'completed'       | 'pending' or       | 'successful-ok' - Job is |
 |                   | 'pending-held'     | started over.            |
 +-------------------+--------------------+--------------------------+
 | 'completed'       | 'completed'        | 'client-error-not-       |
 |                   |                    | possible' - see Rule 1.  |
 +-------------------+--------------------+--------------------------+
 | 'canceled'        | 'pending' or       | 'successful-ok' - Job is |
 |                   | 'pending-held'     | started over.            |
 +-------------------+--------------------+--------------------------+
 | 'canceled'        | 'canceled'         | 'client-error-not-       |
 |                   |                    | possible' - see Rule 1.  |
 +-------------------+--------------------+--------------------------+
 | 'aborted'         | 'pending' or       | 'successful-ok' - Job is |
 |                   | 'pending-held'     | started over.            |
 +-------------------+--------------------+--------------------------+
 | 'aborted'         | 'aborted'          | 'client-error-not-       |
 |                   |                    | possible' - see Rule 1.  |
 +-------------------+--------------------+--------------------------+
                Table 7: Restart-Job State Transitions
 Rule 1: If the Job Retention Period has expired for the Job in this
 state, then the Printer rejects the operation.  See Section 5.3.7.2.

Sweet & McDonald Standards Track [Page 90] RFC 8011 IPP/1.1: Model and Semantics January 2017

4.3.7.1. Restart-Job Request

 The groups and attributes are the same as those defined for a
 Cancel-Job request (see Section 4.3.3.1), with the addition of the
 following Group 1 operation attribute:
    "job-hold-until" (type2 keyword | name(MAX)):
    The Client MAY supply and the Printer MUST support this operation
    attribute in a Restart-Job request if it supports the
    "job-hold-until" Job Template attribute in Job Creation requests.
    See Section 5.2.2.
    If supplied and supported as specified in the Printer's
    "job-hold-until-supported" attribute, the Printer copies the
    supplied operation attribute to the Job, replacing the Job's
    previous "job-hold-until" attribute, if present, and makes the Job
    a candidate for scheduling during the supplied named time period.
    See Section 5.2.2.
    If supplied but the value is not supported, the Printer accepts
    the request, returns the unsupported attribute or value in the
    Unsupported Attributes group according to Section 4.1.7, returns
    the 'successful-ok-ignored-or-substituted-attributes' status-code,
    and holds the Job indefinitely until a Client performs a
    subsequent Release-Job operation.
    If supplied but the "job-hold-until" operation attribute itself is
    not supported, the Printer accepts the request, returns the
    unsupported attribute with the out-of-band 'unsupported' value in
    the Unsupported Attributes group according to Section 4.1.7,
    returns the 'successful-ok-ignored-or-substituted-attributes'
    status-code, and restarts the Job, i.e., ignores the
    "job-hold-until" attribute.
    If (1) the Client supplies either a value that specifies a time
    period that has already started or the 'no-hold' value (meaning
    don't hold the Job) and (2) the Printer supports the
    "job-hold-until" operation attribute and there are no other
    reasons to hold the Job, the Printer makes the Job a candidate for
    processing immediately (see Section 5.2.2).
    If the Client does not supply a "job-hold-until" operation
    attribute in the request, the Printer removes the "job-hold-until"
    attribute, if present, from the Job.  If there are no other
    reasons to hold the Job, the Restart-Job operation makes the Job a
    candidate for processing immediately (see Section 5.2.2).

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4.3.7.2. Restart-Job Response

 The groups and attributes are the same as those defined for a
 Cancel-Job response (see Section 4.3.3.2).

5. Object Attributes

 This section describes the attributes with their corresponding
 attribute syntaxes and values that are part of the IPP Model.  The
 sections below show the objects and their associated attributes that
 are included within the scope of this protocol.  Many of these
 attributes are derived from other relevant documents:
 o  Document Printing Application (DPA) [ISO10175]
 o  Printer MIB v2 [RFC3805]
 Each attribute is uniquely identified in this document using a
 "keyword" (see Section 2.3.7) that is the name of the attribute.  The
 keyword is included in the section title describing that attribute.
 Note: Not only are keywords used to identify attributes, but one of
 the attribute syntaxes described below is "keyword" so that some
 attributes have 'keyword' values.  Therefore, these attributes are
 defined as having an attribute syntax that is a set of keywords.

5.1. Attribute Syntaxes

 This section defines the basic attribute syntax types that all
 Clients and IPP objects MUST be able to accept in responses and
 accept in requests, respectively.  Each attribute description in
 Sections 4 and 5 includes in the section title the name of the
 attribute with its syntax(es) in parentheses.  A conforming
 implementation of an attribute MUST include the semantics of the
 attribute syntax(es) so identified.  Section 7.7 describes how the
 protocol can be extended with new attribute syntaxes.
 The attribute syntaxes are specified in the following subsections,
 where the subsection title is the keyword name of the attribute
 syntax inside the single quotes.  In operation requests and
 responses, each attribute value MUST be represented as one of the
 attribute syntaxes specified in the subsection title for the
 attribute.  In addition, the value of an attribute in a response (but
 not in a request) MAY be one of the "out-of-band" values
 (Section 5.1.1) whose special encoding rules are defined in the
 Encoding and Transport document [RFC8010].

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 All attributes in a request MUST have one or more values as defined
 in Sections 5.2, 5.3, and 5.4.  All attributes in a response MUST
 have either (1) one or more values as defined in Sections 5.2, 5.3,
 and 5.4 or (2) a single "out-of-band" value.
 Most attributes are defined to have a single attribute syntax.
 However, a few attributes (e.g., "job-sheet", "media",
 "job-hold-until") are defined to have several attribute syntaxes,
 depending on the value.  These multiple attribute syntaxes are
 separated by the "|" character in the subsection title to indicate
 the choice.  Since each value MUST be tagged as to its attribute
 syntax in the protocol, a single-valued attribute instance can have
 any one of its attribute syntaxes and a multi-valued attribute
 instance can have a mixture of its defined attribute syntaxes.

5.1.1. Out-of-Band Values - 'unknown', 'unsupported', and 'no-value'

 This document defines three "out-of-band" values that are used in
 place of an attribute's defined syntax:
 o  'unknown': The attribute is supported by the IPP object, but the
    value is unknown to the IPP object for some reason.  This
    out-of-band value is used for attributes that have an intrinsic,
    physical value that cannot be determined by the IPP object at a
    given time, e.g., sheet count, geo-location, etc.
 o  'unsupported': The attribute is unsupported by the IPP object.
    This value MUST be returned only as the value of an attribute in
    the Unsupported Attributes group.
 o  'no-value': The attribute is supported by the Printer, but the
    Administrator has not yet configured a value.

5.1.2. 'text'

 A 'text' attribute is an attribute whose value is a sequence of zero
 or more characters encoded in a maximum of 1023 ('MAX') octets.  MAX
 is the maximum length for each value of any 'text' attribute.
 However, if an attribute will always contain values whose maximum
 length is much less than MAX, the definition of that attribute will
 include a qualifier that defines the maximum length for values of
 that attribute.  For example, the "printer-location" attribute is
 specified as "printer-location (text(127))".  In this case, text
 values for "printer-location" MUST NOT exceed 127 octets; if supplied
 with a longer text string via some external interface (other than the
 protocol), implementations are free to truncate to this shorter
 length limitation.

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 In this document, all 'text' attributes are defined using the 'text'
 syntax.  However, 'text' is used only for brevity; the formal
 interpretation of 'text' is 'textWithoutLanguage | textWithLanguage'.
 That is, for any attribute defined in this document using the 'text'
 attribute syntax, all IPP objects and Clients MUST support both the
 'textWithoutLanguage' and 'textWithLanguage' attribute syntaxes.
 However, in actual usage and protocol execution, IPP objects and
 Clients accept and return only one of the two syntaxes per attribute.
 The syntax 'text' never appears "on-the-wire".
 Both 'textWithoutLanguage' and 'textWithLanguage' are needed to
 support the real-world needs of interoperability between sites and
 systems that use different natural languages as the basis for human
 communication.  Generally, one natural language applies to all 'text'
 attributes in a given request or response.  The language is indicated
 by the "attributes-natural-language" operation attribute defined in
 Section 4.1.4 or the "attributes-natural-language" Job attribute
 defined in Section 5.3.20, and there is no need to identify the
 natural language for each text string on a value-by-value basis.  In
 these cases, the attribute syntax 'textWithoutLanguage' is used for
 'text' attributes.  In other cases, the Client needs to supply or the
 Printer needs to return a text value in a natural language that is
 different from the rest of the text values in the request or
 response.  In these cases, the Client or Printer uses the attribute
 syntax 'textWithLanguage' for 'text' attributes (this is the Natural
 Language Override mechanism described in Section 4.1.4).
 The 'textWithoutLanguage' and 'textWithLanguage' attribute syntaxes
 are described in more detail in the following sections.

5.1.2.1. 'textWithoutLanguage'

 The 'textWithoutLanguage' syntax indicates a value that is a sequence
 of zero or more characters encoded in a maximum of 1023 (MAX) octets.
 Text strings are encoded using the rules of some charset.  The
 Printer MUST support the UTF-8 charset [RFC3629] and MAY support
 additional charsets to represent 'text' values, provided that the
 charsets are registered with IANA [IANA-CS].  See Section 5.1.8 for
 the definition of the 'charset' attribute syntax, including
 restricted semantics and examples of charsets.

5.1.2.2. 'textWithLanguage'

 The 'textWithLanguage' attribute syntax is a compound attribute
 syntax consisting of two parts: a 'textWithoutLanguage' part encoded
 in a maximum of 1023 (MAX) octets plus an additional
 'naturalLanguage' (see Section 5.1.9) part that overrides the natural
 language in force.  The 'naturalLanguage' part explicitly identifies

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 the natural language that applies to the text part of that value and
 that value alone.  For any given 'text' attribute, the
 'textWithoutLanguage' part is limited to the maximum length defined
 for that 'text' attribute, and the 'naturalLanguage' part is always
 limited to 63 (additional) octets.  Using the 'textWithLanguage'
 attribute syntax rather than the normal 'textWithoutLanguage' syntax
 is the so-called "Natural Language Override mechanism" and MUST be
 supported by all IPP objects and Clients.
 If the attribute is multi-valued (1setOf text), then the
 'textWithLanguage' attribute syntax MUST be used to explicitly
 specify each attribute value whose natural language needs to be
 overridden.  Other values in a multi-valued 'text' attribute in a
 request or a response revert to the natural language of the operation
 attribute.
 In a Job Creation request, the Printer MUST accept and store with the
 Job any natural language in the "attributes-natural-language"
 operation attribute, whether the Printer supports that natural
 language or not.  Furthermore, the Printer MUST accept and store any
 'textWithLanguage' attribute value, whether the Printer supports that
 natural language or not.  These requirements are independent of the
 value of the "ipp-attribute-fidelity" operation attribute that the
 Client MAY supply.
 Example: If the Client supplies the "attributes-natural-language"
 operation attribute with the value 'en' indicating English but the
 value of the "job-name" attribute is in French, the Client MUST use
 the 'textWithLanguage' attribute syntax with the following two
 values:
    'fr': Natural Language Override indicating French
    'Rapport Mensuel': the Job name in French
 See the Encoding and Transport document [RFC8010] for the encoding of
 the two parts and a detailed example of the 'textWithLanguage'
 attribute syntax.

5.1.3. 'name'

 This syntax type is used for user-friendly strings, such as a Printer
 name, that, for humans, are more meaningful than identifiers.  Names
 are never translated from one natural language to another.  The
 'name' attribute syntax is essentially the same as 'text', including
 the REQUIRED support of UTF-8, except that the sequence of characters
 is limited so that its encoded form MUST NOT exceed 255 (MAX) octets.

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 Also, like 'text', 'name' is really an abbreviated notation for
 either 'nameWithoutLanguage' or 'nameWithLanguage'.  That is, all IPP
 objects and Clients MUST support both the 'nameWithoutLanguage' and
 'nameWithLanguage' attribute syntaxes.  However, in actual usage and
 protocol execution, IPP objects and Clients accept and return only
 one of the two syntaxes per attribute.  The syntax 'name' never
 appears "on-the-wire".
 Only the 'text' and 'name' attribute syntaxes permit the Natural
 Language Override mechanism.
 Some attributes are defined as 'type2 keyword | name'.  These
 attributes support values that are either type2 keywords or names.
 This dual-syntax mechanism enables a site Administrator to extend
 these attributes to legally include values that are locally defined
 by the site Administrator.  Such names are not registered with IANA.

5.1.3.1. 'nameWithoutLanguage'

 The 'nameWithoutLanguage' syntax indicates a value that is a sequence
 of zero or more characters encoded in a maximum of 255 (MAX) octets.

5.1.3.2. 'nameWithLanguage'

 The 'nameWithLanguage' attribute syntax is a compound attribute
 syntax consisting of two parts: a 'nameWithoutLanguage' (see
 Section 5.1.3.1) part plus an additional 'naturalLanguage' (see
 Section 5.1.9) part that overrides the natural language in force.
 The 'naturalLanguage' part explicitly identifies the natural language
 that applies to that name value and that name value alone.  For any
 given 'name' attribute, the 'nameWithoutLanguage' part is limited to
 the maximum length defined for that 'name' attribute, and the
 'naturalLanguage' part is always limited to 63 (additional) octets.
 Using the 'nameWithLanguage' attribute syntax rather than the normal
 'nameWithoutLanguage' syntax is the Natural Language Override
 mechanism and MUST be supported by all IPP objects and Clients.
 The 'nameWithLanguage' attribute syntax behaves the same as the
 'textWithLanguage' syntax.  If a name is in a language that is
 different than the rest of the object or operation, then this
 'nameWithLanguage' syntax is used rather than the generic
 'nameWithoutLanguage' syntax.
 If the attribute is multi-valued (1setOf name), then the
 'nameWithLanguage' attribute syntax MUST be used to explicitly
 specify each attribute value whose natural language needs to be

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 overridden.  Other values in a multi-valued 'name' attribute in a
 request or a response revert to the natural language of the operation
 attribute.
 In a Job Creation request, the Printer MUST accept and store with the
 Job any natural language in the "attributes-natural-language"
 operation attribute, whether the Printer supports that natural
 language or not.  Furthermore, the Printer MUST accept and store any
 'nameWithLanguage' attribute value, whether the Printer supports that
 natural language or not.  These requirements are independent of the
 value of the "ipp-attribute-fidelity" operation attribute that the
 Client MAY supply.
 Example: If the Client supplies the "attributes-natural-language"
 operation attribute with the value 'en' indicating English but the
 "printer-name" attribute is in German, the Client MUST use the
 'nameWithLanguage' attribute syntax as follows:
    'de': Natural Language Override indicating German
    'Farbdrucker': the Printer name in German
 See the Encoding and Transport document [RFC8010] for the encoding of
 the two parts and a detailed example of the 'nameWithLanguage'
 attribute syntax.

5.1.3.3. Matching 'name' Attribute Values

 For purposes of matching two 'name' attribute values for equality,
 such as in Job validation (where a Client-supplied value for
 attribute "xxx" is checked to see if the value is among the values of
 the Printer's corresponding "xxx-supported" attribute), the following
 match rules apply:
 1.  'keyword' values never match 'name' values.
 2.  'name' ('nameWithoutLanguage' and 'nameWithLanguage') values
     match if (1) the name parts match and (2) the Associated
     Natural Language parts (see Section 4.1.4.1) match.  The matching
     rules are as follows:
     2a.  The name parts match if the two names are identical
          character by character, except that it is RECOMMENDED that
          case be ignored as defined in "i;unicode-casemap - Simple
          Unicode Collation Algorithm" [RFC5051].  For example,
          'Ajax-letter-head-white' MUST match 'Ajax-letter-head-white'
          and SHOULD match 'ajax-letter-head-white' and
          'AJAX-LETTER-HEAD-WHITE'.

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     2b.  The Associated Natural Language parts match if the shorter
          of the two meets the syntactic requirements defined in
          Section 2.1 of RFC 5646 [RFC5646] and matches (byte for
          byte, since IPP language tags are lowercase) with the
          longer.  For example, 'en' matches 'en', 'en-us', and
          'en-gb' but matches neither 'fr' nor 'e'.

5.1.4. 'keyword'

 The 'keyword' attribute syntax is a sequence of characters, of length
 1 to 255, containing only the US-ASCII [RFC20] encoded values for
 lowercase letters ("a"-"z"), digits ("0"-"9"), hyphen ("-"), dot
 ("."), and underscore ("_").  The first character MUST be a lowercase
 letter.  Furthermore, keywords MUST be in US English.
 This syntax type is used for enumerating semantic identifiers of
 entities in the abstract protocol, i.e., entities identified in this
 document.  Keywords are used as attribute names or values of
 attributes.  Unlike 'text' and 'name' attribute values, 'keyword'
 values MUST NOT use the Natural Language Override mechanism, since
 they MUST always be US-ASCII and US English.
 Keywords are for use in the protocol.  A user interface will likely
 provide a mapping between protocol keywords and displayable
 user-friendly words and phrases that are localized to the natural
 language of the user.  While the keywords specified in this document
 MAY be displayed to users whose natural language is US English, they
 MAY be mapped to other US English words for US English users, since
 the user interface is outside the scope of this document.
 In the definition for each attribute of this syntax type, the full
 set of 'keyword' values being defined for that attribute is listed.
 The IANA IPP registry will always contain the complete and current
 list of 'keyword' values for the attribute.
 When a keyword is used to represent an attribute (its name), it MUST
 be unique within the full scope of all IPP objects and attributes.
 When a keyword is used to represent a value of an attribute, it MUST
 be unique just within the scope of that attribute.  That is, the same
 keyword MUST NOT be used for two different values within the same
 attribute to mean two different semantic ideas.  However, the same
 keyword MAY be used across two or more attributes, representing

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 different semantic ideas for each attribute.  Section 7.3 describes
 how the protocol can be extended with new 'keyword' values.  Examples
 of attribute name keywords are:
    "job-name"
    "attributes-charset"
 Note: This document uses "type1" and "type2" prefixes to the
 "keyword" basic syntax to indicate different levels of review for
 extensions (see Section 7.3).

5.1.5. 'enum'

 The 'enum' attribute syntax is an enumerated integer value that is in
 the range from 1 to 2**31 - 1 (MAX).  Each value has an associated
 'keyword' name.  In the definition for each attribute of this syntax
 type, the full set of possible values for that attribute is listed.
 This syntax type is used for attributes for which there are enum
 values assigned by other standards, such as SNMP MIBs.  A number of
 attribute enum values in this document are also used for
 corresponding attributes in other standards [RFC3805].  This syntax
 type is not used for attributes to which the Administrator can assign
 values.  Section 7.4 describes how the protocol can be extended with
 new enum values.
 Enum values are for use in the protocol.  A user interface will
 provide a mapping between protocol enum values and displayable
 user-friendly words and phrases that are localized to the natural
 language of the user.  While the enum symbols specified in this
 document MAY be displayed to users whose natural language is
 US English, they MAY be mapped to other US English words for
 US English users, since the user interface is outside the scope of
 this document.
 Note: Some SNMP MIBs use '2' for 'unknown', which corresponds to the
 IPP "out-of-band" value 'unknown'.  See the description of the
 "out-of-band" values at the beginning of Section 5.1.  Therefore,
 attributes of type 'enum' typically start at '3'.
 Note: This document uses "type1" and "type2" prefixes to the "enum"
 basic syntax to indicate different levels of review for extensions
 (see Section 7.4).

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5.1.6. 'uri'

 The 'uri' attribute syntax is any valid Uniform Resource Identifier
 (URI) [RFC3986].  Most often, URIs are simply Uniform Resource
 Locators (URLs).  The maximum length of URIs used as values of IPP
 attributes is 1023 octets.  Although most other IPP attribute syntax
 types allow for only lowercase values, this attribute syntax type
 conforms to the case-sensitive and case-insensitive rules specified
 in [RFC3986].  See also [RFC3196] for a discussion of case in URIs.

5.1.7. 'uriScheme'

 The 'uriScheme' attribute syntax is a sequence of characters
 representing a URI scheme according to RFC 3986 [RFC3986].  Though
 RFC 3986 requires that the values be case insensitive, IPP requires
 all lowercase values in IPP attributes, to simplify comparing by IPP
 Clients and Printers.
 Standard values for this syntax type include the following keywords:
 o  'ipp': for IPP schemed URIs, e.g., "ipp://example.com/ipp/..."
    [RFC3510]
 o  'ipps': for IPPS schemed URIs, e.g., "ipps://example.com/ipp/..."
    [RFC7472]
 o  'http': for HTTP schemed URIs, e.g., "http://example.com/path/to/
    filename" [RFC7230]
 o  'https': for HTTPS schemed URIs, e.g.,
    "https://example.com/path/to/filename" [RFC7230]
 o  'ftp': for FTP schemed URIs, e.g., "ftp://example.com/path/to/
    filename" [RFC1738]
 o  'mailto': for SMTP schemed URIs, e.g., "mailto:user@example.com"
    [RFC6068]
 o  'file': for file schemed URIs, e.g., "file:///path/to/filename"
    [RFC1738]
 o  'urn': for Uniform Resource Name schemed URIs, e.g.,
    "urn:uuid:01234567-89ab-cdef-fedc-ba9876543210" [RFC4122]
 A Printer MAY support any URI 'scheme' that has been registered with
 IANA [IANA-MT].  The maximum length of URI 'scheme' values used to
 represent IPP attribute values is 63 octets.

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5.1.8. 'charset'

 The 'charset' attribute syntax is a standard identifier for a
 charset.  A charset is a coded character set and encoding scheme.
 Charsets are used for labeling certain Document contents, 'text'
 attribute values, and 'name' attribute values.  The syntax and
 semantics of this attribute syntax are specified in RFC 2046
 [RFC2046] and contained in the IANA "Character Sets" registry
 [IANA-CS] according to the IANA procedures [RFC2978].  Though
 RFC 2046 requires that the values be case-insensitive US-ASCII
 [RFC20], IPP requires all lowercase values in IPP attributes, to
 simplify comparing by IPP Clients and Printers.  When a character set
 in the IANA registry has more than one name (alias), the name labeled
 as "(preferred MIME name)", if present, MUST be used.
 The maximum length of 'charset' values used to represent IPP
 attribute values is 63 octets.
 Some examples are:
 o  'utf-8': ISO 10646 Universal Multiple-Octet Coded Character Set
    (UCS) [ISO10646] represented as the UTF-8 [RFC3629] transfer
    encoding scheme in which US-ASCII [RFC20] is a subset charset.
 o  'us-ascii': 7-bit American Standard Code for Information
    Interchange (ASCII) [RFC20].
 o  'iso-8859-1': 8-bit One-Byte Coded Character Set, Latin Alphabet
    No. 1 [ISO8859-1].  That standard defines a coded character set
    that is used by Latin languages in the Western Hemisphere and
    Western Europe.  US-ASCII is a subset charset.
 Some attribute descriptions MAY place additional requirements on
 charset values that can be used, such as REQUIRED values that MUST be
 supported or additional restrictions, such as requiring that the
 charset have US-ASCII as a subset charset.

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5.1.9. 'naturalLanguage'

 The 'naturalLanguage' attribute syntax is a standard identifier for a
 natural language and, optionally, a country or region.  The values
 for this syntax type are defined by RFC 5646 [RFC5646].  Though
 RFC 5646 requires that the values be case-insensitive US-ASCII, IPP
 requires all lowercase values in IPP attributes, to simplify
 comparing by IPP Clients and Printers.  Examples include:
 o  'en': for English
 o  'en-us': for US English
 o  'fr': for French
 o  'de': for German
 The maximum length of 'naturalLanguage' values used to represent IPP
 attribute values is 63 octets.
 Note: While any standard natural language identifier defined in
 RFC 5646 can be used, Clients typically only support a subset of
 these identifiers.  When comparing two identifiers or performing
 lookups, Printers SHOULD be prepared to match legacy identifiers with
 their corresponding modern equivalents and vice versa.

5.1.10. 'mimeMediaType'

 The 'mimeMediaType' attribute syntax is the Internet media type
 (sometimes called "MIME type") as defined by RFC 2046 [RFC2046] and
 registered according to the procedures of RFC 6838 [RFC6838] for
 identifying a Document format.  The value MAY include a charset
 parameter, or some other parameter, depending on the specification of
 the media type in the IANA "Media Types" registry [IANA-MT].
 Although most other IPP syntax types allow for only lowercase values,
 this syntax type allows for mixed-case values that are
 case insensitive.
 Examples are:
 o  'text/html': An HTML Document
 o  'text/plain': A plain text Document in US-ASCII (RFC 2046
    indicates that in the absence of the charset parameter MUST mean
    US-ASCII rather than simply unspecified) [RFC2046]
 o  'text/plain; charset = US-ASCII': A plain text Document in
    US-ASCII

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 o  'text/plain; charset = ISO-8859-1': A plain text Document in
    ISO 8859-1 (Latin 1) [ISO8859-1]
 o  'text/plain; charset = utf-8': A plain text Document in ISO 10646
    represented as UTF-8 [RFC3629]
 o  'application/postscript': A PostScript Document [RFC2046]
 o  'application/vnd.hp-PCL': A PCL Document [IANA-MT] (charset escape
    sequence embedded in the Document data)
 o  'application/pdf': Portable Document Format [ISO32000]
 o  'application/octet-stream': Auto-sense - see Section 5.1.10.1
 The maximum length of a 'mimeMediaType' value to represent IPP
 attribute values is 255 octets.

5.1.10.1. 'application/octet-stream' - Auto-Sensing the Document Format

 One special type is 'application/octet-stream'.  If the Printer
 supports this value, the Printer MUST be capable of auto-sensing the
 format of the Document data using an implementation-dependent method
 that examines some number of octets of the Document data, either as
 part of the Job Creation request and/or at Document processing time.
 During auto-sensing, a Printer can determine that the Document data
 has a format that the Printer doesn't recognize.  If the Printer
 determines this problem before returning an operation response, it
 rejects the request and returns the
 'client-error-document-format-not-supported' status-code.  If the
 Printer determines this problem after accepting the request and
 returning an operation response with one of the successful
 status-code values, the Printer adds the
 'unsupported-document-format' value to the Job's "job-state-reasons"
 attribute.
 If the Printer's default value attribute "document-format-default" is
 set to 'application/octet-stream', the Printer not only supports
 auto-sensing of the Document format but will depend on the result of
 applying its auto-sensing when the Client does not supply the
 "document-format" attribute.  If the Client supplies a Document
 format value, the Printer MUST rely on the supplied attribute, rather
 than trust its auto-sensing algorithm.  To summarize:
 1.  If the Client does not supply a Document format value, the
     Printer MUST rely on its default value setting (which can be
     'application/octet-stream' indicating an auto-sensing mechanism).

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 2.  If the Client supplies a value other than
     'application/octet-stream', the Client is supplying valid
     information about the format of the Document data and the Printer
     MUST trust the Client-supplied value more than the outcome of
     applying an automatic format detection mechanism.  For example,
     the Client can request the printing of a PostScript file as a
     'text/plain' Document.  The Printer MUST print a text
     representation of the PostScript commands rather than interpret
     the stream of PostScript commands and print the result.
 3.  If the Client supplies a value of 'application/octet-stream', the
     Client is indicating that the Printer MUST use its auto-sensing
     mechanism on the Client-supplied Document data whether
     auto-sensing is the Printer's default or not.
 Note: Since the auto-sensing algorithm is probabilistic, if the
 Client requests both auto-sensing ("document-format" set to
 'application/octet-stream') and true fidelity
 ("ipp-attribute-fidelity" set to 'true'), the Printer might not be
 able to guarantee exactly what the End User intended (the
 auto-sensing algorithm might mistake one Document format for
 another), but it is able to guarantee that its auto-sensing mechanism
 will be used.

5.1.11. 'octetString'

 The 'octetString' attribute syntax is a sequence of octets encoded in
 a maximum of 1023 octets that is indicated in syntax definitions
 using the notation 'octetString(MAX)'.  This syntax type is used for
 opaque data.

5.1.12. 'boolean'

 The 'boolean' attribute syntax has only two values: 'true' and
 'false'.

5.1.13. 'integer'

 The 'integer' attribute syntax is an integer value that is in the
 range from -2**31 (MIN) to 2**31 - 1 (MAX).  Each individual
 attribute can specify the range constraint explicitly if the range is
 different from the full range of possible integer values -- for
 example, job-priority (integer(1:100)) for the "job-priority"
 attribute, as shown in the title of Section 5.2.1.  However, the
 enforcement of that additional constraint is up to the IPP objects,
 not the protocol.

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5.1.14. 'rangeOfInteger'

 The 'rangeOfInteger' attribute syntax is an ordered pair of integers
 that defines an inclusive range of integer values.  The first integer
 specifies the lower bound, and the second specifies the upper bound.
 If a range constraint is specified in the attribute definition, i.e.,
 'rangeOfInteger(X:Y)' indicating X as a minimum value and Y as a
 maximum value, then the constraint applies to both integers.

5.1.15. 'dateTime'

 The 'dateTime' attribute syntax is a standard, fixed-length, 11-octet
 representation of the "DateAndTime" syntax as defined in RFC 2579
 [RFC2579].  RFC 2579 also identifies an 8-octet representation of a
 "DateAndTime" value, but IPP objects MUST use the 11-octet
 representation.  A user interface will provide a mapping between
 protocol dateTime values and displayable user-friendly words or
 presentation values and phrases that are localized to the natural
 language and date format of the user, including time zone.

5.1.16. 'resolution'

 The 'resolution' attribute syntax specifies a two-dimensional
 resolution in the indicated units.  It consists of three values: a
 cross-feed direction resolution (positive integer value), a feed
 direction resolution (positive integer value), and a units value.
 The semantics of these three components are taken from the suggested
 values in the Printer MIB [RFC3805].  That is, the cross-feed
 direction resolution component is the same as the
 prtMarkerAddressabilityXFeedDir object in the Printer MIB, the feed
 direction resolution component is the same as the
 prtMarkerAddressabilityFeedDir in the Printer MIB, and the units
 component is the same as the prtMarkerAddressabilityUnit object in
 the Printer MIB (namely, '3' indicates dots per inch and '4'
 indicates dots per centimeter).  All three values MUST be present
 even if the first two values are the same.  For example, '300',
 '600', '3' indicates a 300-dpi cross-feed direction resolution and a
 600-dpi feed direction resolution, since a '3' indicates dots per
 inch (dpi).

5.1.17. 'collection'

 The 'collection' attribute syntax is a container holding one or more
 named values (i.e., attributes), which are called "member
 attributes".  Each 'collection' attribute definition Document lists
 the mandatory and optional member attributes of each collection
 value.  A collection value is similar to an IPP attribute group in a

Sweet & McDonald Standards Track [Page 105] RFC 8011 IPP/1.1: Model and Semantics January 2017

 request or a response, such as the Operation Attributes group -- they
 both consist of a set of attributes.  Collections can also be nested,
 i.e., a collection in a collection.
 A collection value consists of three separate components:
 o  A 'begCollection' value with an optional octet string value
    starting the collection,
 o  Zero or more member attributes defined using a series of unnamed
    values starting with a 'memberAttrName' value that specifies the
    member attribute name, and
 o  An 'endCollection' value with an optional name plus octet string
    value finishing the collection.

5.1.18. '1setOf X'

 The '1setOf X' attribute syntax is one or more values of attribute
 syntax type X.  This syntax type is used for multi-valued attributes.
 The syntax type is called '1setOf' rather than just 'setOf' as a
 reminder that the set of values MUST NOT be empty (i.e., a set of
 size 0).  Sets are normally unordered; however, each attribute
 description of this type can specify that the values MUST be in a
 certain order for that attribute.

5.2. Job Template Attributes

 Job Template attributes describe Job processing intent.  Clients MAY
 supply (in Job Creation requests) and Printers SHOULD support Job
 Template attributes.  See Section 2.3.11 for a description of support
 for OPTIONAL attributes.
 Job Template attributes conform to the following rules.  For each Job
 Template attribute called "xxx":
 1.  If the Printer supports "xxx", then it MUST support both an
     "xxx-default" attribute (unless there is a "No" in Table 8 below)
     and an "xxx-supported" attribute.  If the Printer doesn't support
     "xxx", then it MUST support neither an "xxx-default" attribute
     nor an "xxx-supported" attribute, and it MUST treat an attribute
     "xxx" supplied by a Client as unsupported.  An attribute "xxx"
     can be supported for some Document formats and not supported for
     other Document formats.  For example, it is expected that a
     Printer would only support "orientation-requested" for some
     Document formats (such as 'text/plain' or 'text/html') but not
     others (such as 'application/postscript').

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 2.  Clients MAY supply "xxx" in a Job Creation request.  If "xxx" is
     supplied, the Client is indicating a desired Job processing
     behavior for this Job.  When "xxx" is not supplied, the Client is
     indicating that the Printer apply its default Job processing
     behavior at Job processing time if the Document content does not
     contain an embedded instruction indicating an xxx-related
     behavior.
     Since an Administrator MAY change the default value attribute
     after a Job has been submitted but before it has been processed,
     the default value used by the Printer at Job processing time can
     be different than the default value in effect at Job submission
     time.
 3.  The "xxx-supported" attribute is a Printer attribute that
     describes which Job processing behaviors are supported by that
     Printer.  A Client can query the Printer to find out what
     xxx-related behaviors are supported by inspecting the returned
     values of the "xxx-supported" attribute.
     Note: The "xxx" in each "xxx-supported" attribute name is
     singular, even though an "xxx-supported" attribute usually has
     more than one value, such as "print-quality-supported", unless
     the "xxx" Job Template attribute is plural, such as "finishings"
     or "sides".  In such cases, the "xxx-supported" attribute names
     are "finishings-supported" and "sides-supported".
 4.  The "xxx-default" default value attribute describes what will be
     done at Job processing time when no other Job processing
     information is supplied by the Client (either explicitly as an
     IPP attribute in the Job Creation request or implicitly as an
     embedded instruction within the Document data).
 If an application wishes to present an End User with a list of
 supported values from which to choose, the application SHOULD query
 the Printer for its supported value attributes.  The application
 SHOULD also query the default value attributes.  If the application
 then limits selectable values to only those values that are
 supported, the application can guarantee that the values supplied by
 the Client in the Job Creation request all fall within the set of
 supported values at the Printer.  When querying the Printer, the
 Client MAY enumerate each attribute by name in the
 Get-Printer-Attributes request, or the Client MAY just name the
 "job-template" group in order to get the complete set of supported
 attributes (both supported and default attributes).

Sweet & McDonald Standards Track [Page 107] RFC 8011 IPP/1.1: Model and Semantics January 2017

 The "finishings" attribute is an example of a Job Template attribute.
 It can take on a set of values such as '4' ('staple'), '5' ('punch'),
 and/or '6' ('cover'); see Table 10 in Section 5.2.6.  A Client can
 query the Printer for the "finishings-supported" attribute and the
 "finishings-default" attribute.  The supported attribute contains a
 set of supported values.  The default value attribute contains the
 finishing value(s) that will be used for a new Job if the Client does
 not supply a "finishings" attribute in the Job Creation request and
 the Document data does not contain any corresponding finishing
 instructions.  If the Client does supply the "finishings" attribute
 in the Job Creation request, the Printer validates the value or
 values to make sure that they are a subset of the supported values
 identified in the Printer's "finishings-supported" attribute.  See
 Section 4.1.7.
 Table 8 below summarizes the names and relationships for all Job
 Template attributes.  The first column of the table (labeled "Job
 Attribute") shows the name and syntax for each Job Template attribute
 in the Job.  These are the attributes that can optionally be supplied
 by the Client in a Job Creation request.  The last two columns
 (labeled "Printer: Default Value Attribute" and "Printer: "Supported
 Values" Attribute") show the name and syntax for each Job Template
 attribute in the Printer (the default value attributes and the
 "supported values" attributes).  A "No" in the table means the
 Printer MUST NOT support the attribute (that is, the attribute is
 simply not applicable).  For brevity in the table, the 'text' and
 'name' entries do not show the maximum length for each attribute.
 +------------------+----------------------+-------------------------+
 | Job Attribute    | Printer: Default     | Printer: "Supported     |
 |                  | Value Attribute      | Values" Attribute       |
 +------------------+----------------------+-------------------------+
 | job-priority     | job-priority-default | job-priority-supported  |
 | (integer 1:100)  | (integer 1:100)      | (integer 1:100)         |
 +------------------+----------------------+-------------------------+
 | job-hold-until   | job-hold-until-      | job-hold-until-         |
 | (type2 keyword | | default (type2       | supported (1setOf       |
 | name)            | keyword | name)      | (type2 keyword | name)) |
 +------------------+----------------------+-------------------------+
 | job-sheets       | job-sheets-default   | job-sheets-supported    |
 | (type2 keyword | | (type2 keyword |     | (1setOf (type2 keyword  |
 | name)            | name)                | | name))                |
 +------------------+----------------------+-------------------------+
 | multiple-        | multiple-document-   | multiple-document-      |
 | document-        | handling-default     | handling-supported      |
 | handling (type2  | (type2 keyword)      | (1setOf type2 keyword)  |
 | keyword)         |                      |                         |

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 +------------------+----------------------+-------------------------+
 | copies           | copies-default       | copies-supported        |
 | (integer(1:MAX)) | (integer(1:MAX))     | (rangeOfInteger(1:MAX)) |
 +------------------+----------------------+-------------------------+
 | finishings       | finishings-default   | finishings-supported    |
 | (1setOf type2    | (1setOf type2 enum)  | (1setOf type2 enum)     |
 | enum)            |                      |                         |
 +------------------+----------------------+-------------------------+
 | page-ranges      | No                   | page-ranges-supported   |
 | (1setOf          |                      | (boolean)               |
 | rangeOfInteger   |                      |                         |
 | (1:MAX))         |                      |                         |
 +------------------+----------------------+-------------------------+
 | sides (type2     | sides-default (type2 | sides-supported (1setOf |
 | keyword)         | keyword)             | type2 keyword)          |
 +------------------+----------------------+-------------------------+
 | number-up        | number-up-default    | number-up-supported     |
 | (integer(1:MAX)) | (integer(1:MAX))     | (1setOf                 |
 |                  |                      | (integer(1:MAX) |       |
 |                  |                      | rangeOfInteger(1:MAX))) |
 +------------------+----------------------+-------------------------+
 | orientation-     | orientation-         | orientation-requested-  |
 | requested (type2 | requested-default    | supported (1setOf type2 |
 | enum)            | (type2 enum)         | enum)                   |
 +------------------+----------------------+-------------------------+
 | media (type2     | media-default (type2 | media-supported (1setOf |
 | keyword | name)  | keyword | name)      | (type2 keyword | name)) |
 |                  |                      | media-ready (1setOf     |
 |                  |                      | (type2 keyword | name)) |
 +------------------+----------------------+-------------------------+
 | printer-         | printer-resolution-  | printer-resolution-     |
 | resolution       | default (resolution) | supported (1setOf       |
 | (resolution)     |                      | resolution)             |
 +------------------+----------------------+-------------------------+
 | print-quality    | print-quality-       | print-quality-supported |
 | (type2 enum)     | default (type2 enum) | (1setOf type2 enum)     |
 +------------------+----------------------+-------------------------+
                   Table 8: Job Template Attributes

5.2.1. job-priority (integer(1:100))

 This attribute specifies a priority for scheduling the Job.  A higher
 value specifies a higher priority.  The value 1 indicates the lowest
 possible priority.  The value 100 indicates the highest possible
 priority.  Among those Jobs that are ready to print, a Printer MUST
 print all Jobs with a priority value of n before printing those with
 a priority value of n - 1 for all n.

Sweet & McDonald Standards Track [Page 109] RFC 8011 IPP/1.1: Model and Semantics January 2017

 If the Printer supports this attribute, it MUST always support the
 full range from 1 to 100.  No administrative restrictions are
 permitted.  This way, an End User can always make full use of the
 entire range with any Printer.  If privileged Jobs are implemented
 outside IPP, they MUST have priorities higher than 100, rather than
 restricting the range available to End Users.
 If the Client does not supply this attribute and this attribute is
 supported by the Printer, the Printer MUST use the value of the
 Printer's "job-priority-default" attribute at Job submission time
 (unlike most Job Template attributes that are used if necessary at
 Job processing time).
 The syntax for the "job-priority-supported" attribute is also
 integer(1:100).  This single integer value indicates the number of
 priority levels supported.  The Printer MUST take the value supplied
 by the Client and map it to the closest integer in a sequence of
 n integer values that are evenly distributed over the range from
 1 to 100 using the formula:
    roundToNearestInt((100x + 50) / n)
 where n is the value of "job-priority-supported" and x ranges from
 0 through (n - 1).
 For example, if n = 1, the sequence of values is 50; if n = 2, the
 sequence of values is 25 and 75; if n = 3, the sequence of values is
 17, 50, and 83; if n = 10, the sequence of values is 5, 15, 25, 35,
 45, 55, 65, 75, 85, and 95; if n = 100, the sequence of values is
 1, 2, 3, ... 100.

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 Table 9 shows how a Printer maps Client-supplied "job-priority"
 values for example values of n.
               +--------------+-------+-------+--------+
               | job-priority | n = 1 | n = 2 | n = 10 |
               +--------------+-------+-------+--------+
               | 1            | 50    | 17    | 5      |
               +--------------+-------+-------+--------+
               | 10           | 50    | 17    | 5      |
               +--------------+-------+-------+--------+
               | 20           | 50    | 17    | 15     |
               +--------------+-------+-------+--------+
               | 30           | 50    | 17    | 25     |
               +--------------+-------+-------+--------+
               | 40           | 50    | 50    | 35     |
               +--------------+-------+-------+--------+
               | 50           | 50    | 50    | 45     |
               +--------------+-------+-------+--------+
               | 60           | 50    | 50    | 55     |
               +--------------+-------+-------+--------+
               | 70           | 50    | 50    | 65     |
               +--------------+-------+-------+--------+
               | 80           | 50    | 83    | 75     |
               +--------------+-------+-------+--------+
               | 90           | 50    | 83    | 85     |
               +--------------+-------+-------+--------+
               | 100          | 50    | 83    | 95     |
               +--------------+-------+-------+--------+
                    Table 9: "job-priority" Values

5.2.2. job-hold-until (type2 keyword | name(MAX))

 This attribute specifies the named time period during which the Job
 MUST become a candidate for printing.
 Standard 'keyword' values for named time periods are:
 o  'no-hold': immediately, if there are no other reasons to hold
    the job
 o  'indefinite': the Job is held indefinitely, until a Client
    performs a Release-Job (Section 4.3.6)
 o  'day-time': during the day
 o  'evening': evening

Sweet & McDonald Standards Track [Page 111] RFC 8011 IPP/1.1: Model and Semantics January 2017

 o  'night': night
 o  'weekend': weekend
 o  'second-shift': second shift (after close of business)
 o  'third-shift': third shift (after midnight)
 An Administrator MUST associate allowable print times with a named
 time period (by means outside the scope of this IPP/1.1 document).
 An Administrator is encouraged to pick names that suggest the type of
 time period.  An Administrator MAY define additional values using the
 'name' or 'keyword' attribute syntax, depending on implementation.
 If the value of this attribute specifies a time period that is in the
 future, the Printer SHOULD add the "job-hold-until-specified" value
 to the Job's "job-state-reasons" attribute, MUST move the Job to the
 'pending-held' state, and MUST NOT schedule the Job for printing
 until the specified time period arrives.
 When the specified time period arrives, the Printer MUST remove the
 "job-hold-until-specified" value from the Job's "job-state-reasons"
 attribute, if present.  If there are no other Job state reasons that
 keep the Job in the 'pending-held' state, the Printer MUST consider
 the Job as a candidate for processing by moving the Job to the
 'pending' state.
 If this Job attribute value is the named value 'no-hold' or the
 specified time period has already started, the Job MUST be a
 candidate for processing immediately.
 If the Client does not supply this attribute and this attribute is
 supported by the Printer, the Printer MUST use the value of the
 Printer's "job-hold-until-default" at Job submission time (unlike
 most Job Template attributes that are used if necessary at Job
 processing time).

5.2.3. job-sheets (type2 keyword | name(MAX))

 This attribute determines which Job start/end sheet(s), if any, MUST
 be printed with a Job.
 Standard 'keyword' values are:
 o  'none': no Job sheet is printed
 o  'standard': one or more site-specific standard Job sheets are
    printed, e.g., a single start sheet or both start and end sheets

Sweet & McDonald Standards Track [Page 112] RFC 8011 IPP/1.1: Model and Semantics January 2017

 An Administrator MAY define additional values using the 'name' or
 'keyword' attribute syntax, depending on implementation.
 The effect of this attribute on Jobs with multiple Documents MAY be
 affected by the "multiple-document-handling" Job attribute
 (Section 5.2.4), depending on the Job sheet semantics.

5.2.4. multiple-document-handling (type2 keyword)

 This RECOMMENDED attribute controls which Impressions and Media
 Sheets constitute a Set for copy generation and finishing processes.
 When the value of the "copies" attribute exceeds '1', it also
 controls the order in which the copies that result from processing
 the Documents are produced.  For the purposes of this explanation, if
 "a" represents an instance of Document data, then the result of
 processing the data in Document "a" is a sequence of Media Sheets
 represented by "a(*)".  This attribute MUST be supported with at
 least one value if the Printer supports multiple Documents per Job
 (see Sections 4.2.4 and 4.3.1).
 Standard 'keyword' values are:
 o  'single-document': If a Job has multiple Documents, say, the
    Document data is called "a" and "b", then the result of processing
    all the Document data (a and then b) MUST be treated as a single
    sequence of Media Sheets for finishing processes; that is,
    finishing is performed on the concatenation of the sequences
    a(*),b(*).  The Printer MUST NOT force the data in each Document
    instance to be formatted onto a new Impression, nor to start a new
    Impression on a new Media Sheet.  If more than one copy is made,
    the ordering of the sets of Media Sheets resulting from processing
    the Document data MUST be a(*), b(*), a(*), b(*), ..., and the
    Printer MUST force each copy (a(*),b(*)) to start on a new Media
    Sheet.
 o  'separate-documents-uncollated-copies': If a Job has multiple
    Documents, say, the Document data is called "a" and "b", then the
    result of processing the data in each Document instance MUST be
    treated as a single sequence of Media Sheets for finishing
    processes; that is, the sets a(*) and b(*) would each be finished
    separately.  The Printer MUST force each copy of the result of
    processing the data in a single Document to start on a new Media
    Sheet.  If more than one copy is made, the ordering of the sets of
    Media Sheets resulting from processing the Document data MUST be
    a(*), a(*), ..., b(*), b(*), ... .

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 o  'separate-documents-collated-copies': If a Job has multiple
    Documents, say, the Document data is called "a" and "b", then the
    result of processing the data in each Document instance MUST be
    treated as a single sequence of Media Sheets for finishing
    processes; that is, the sets a(*) and b(*) would each be finished
    separately.  The Printer MUST force each copy of the result of
    processing the data in a single Document to start on a new Media
    Sheet.  If more than one copy is made, the ordering of the sets of
    Media Sheets resulting from processing the Document data MUST be
    a(*), b(*), a(*), b(*), ... .
 o  'single-document-new-sheet': Same as 'single-document', except
    that the Printer MUST ensure that the first Impression of each
    Document instance in the Job is placed on a new Media Sheet.  This
    value allows multiple Documents to be stapled together with a
    single staple where each Document starts on a new Media Sheet.
 The 'single-document' value is the same as
 'separate-documents-collated-copies' with respect to the ordering of
 Input Pages, but not Media Sheet generation, since 'single-document'
 will put the first page of the next Document on the back side of a
 Media Sheet if an odd number of pages have been produced so far for
 the Job, while 'separate-documents-collated-copies' always forces the
 next Document or Document copy on to a new Media Sheet.  In addition,
 if the "finishings" attribute specifies 'staple', then with
 'single-document', Documents a and b are stapled together as a single
 Set with no regard to a new Media Sheet, while with
 'single-document-new-sheet', Documents a and b are stapled together
 as a single Set but Document b starts on a new Media Sheet.  With
 'separate-documents-uncollated-copies' and
 'separate-documents-collated-copies', Documents a and b are stapled
 separately.
 Note: The value 'separate-documents-uncollated-copies' produces
 uncollated Media Sheets within a Set, e.g., when "copies" is '2' a
 two-Document Job will be printed as Media Sheets a(1), a(1), a(2),
 a(2), ... a(n), a(n), b(1), b(1), ..., b(n), b(n).  All other values
 produce collated Media Sheets within a Set.
 The relationship of this attribute and the other attributes that
 control Document processing is described in Appendix C.3.

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5.2.5. copies (integer(1:MAX))

 This RECOMMENDED attribute specifies the number of copies to be
 printed.
 On many devices, the supported number of collated copies will be
 limited by the number of physical output bins on the device and can
 be different from the number of uncollated copies that can be
 supported.
 Note: The effect of this attribute on Jobs with multiple Documents is
 controlled by the "multiple-document-handling" Job attribute
 (Section 5.2.4).  The relationship of this attribute and the other
 attributes that control Document processing is described in
 Appendix C.3.

5.2.6. finishings (1setOf type2 enum)

 This RECOMMENDED attribute identifies the finishing processes that
 the Printer uses for each copy of each printed Document in the Job.
 For Jobs with multiple Documents, the "multiple-document-handling"
 attribute determines what constitutes a "copy" for purposes of
 finishing.
 Standard enum values defined in this document are listed in Table 10.
 The 'staple-xxx' values are specified with respect to the Document as
 if the Document were in portrait orientation with the origin of each
 Media Sheet at the top left corner.  If the Document is actually in
 landscape or reverse-landscape orientation, the Client supplies the
 appropriate transformed value.  For example, to position a staple in
 the upper left-hand corner of a landscape Document when held for
 reading, the Client supplies the 'staple-bottom-left' value, since
 landscape is defined as a +90 degree rotation of the image with
 respect to the media from portrait, i.e., counterclockwise.  On the
 other hand, to position a staple in the upper left-hand corner of a
 reverse-landscape Document when held for reading, the Client supplies
 the 'staple-top-right' value, since reverse-landscape is defined as
 a -90 degree rotation of the image with respect to the media from
 portrait, i.e., clockwise.
 The angle (vertical, horizontal, angled) of each staple with respect
 to the Document depends on the implementation, which can in turn
 depend on the value of the attribute.

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 Note: The effect of this attribute on Jobs with multiple Documents is
 controlled by the "multiple-document-handling" Job attribute
 (Section 5.2.4).  The relationship of this attribute and the other
 attributes that control Document processing is described in
 Appendix C.3.
 Note: The value of '3' ('none') has no effect when combined with any
 other values.
 Note: The "finishings-col" attribute [PWG5100.1] is an alternative to
 the "finishings" attribute that allows the Client to specify
 finishing intent in greater detail.
 +-----------+-------------------------------------------------------+
 | Value     | Symbolic Name and Description                         |
 +-----------+-------------------------------------------------------+
 | '3'       | 'none': Perform no finishing.                         |
 +-----------+-------------------------------------------------------+
 | '4'       | 'staple': Bind the Document(s) with one or more       |
 |           | staples.  The exact number and placement of the       |
 |           | staples are site defined.                             |
 +-----------+-------------------------------------------------------+
 | '5'       | 'punch': This value indicates that holes are required |
 |           | in the finished Document.  The exact number and       |
 |           | placement of the holes are site defined.  The punch   |
 |           | specification MAY be satisfied (in a site-specific    |
 |           | and implementation-specific manner) either by         |
 |           | drilling/punching or by substituting pre-drilled      |
 |           | media.                                                |
 +-----------+-------------------------------------------------------+
 | '6'       | 'cover': This value is specified when it is desired   |
 |           | to select a non-printed (or pre-printed) cover for    |
 |           | the Document.  This does not supplant the             |
 |           | specification of a printed cover (on cover stock      |
 |           | medium) by the Document itself.                       |
 +-----------+-------------------------------------------------------+
 | '7'       | 'bind': This value indicates that a binding is to be  |
 |           | applied to the Document; the type and placement of    |
 |           | the binding are site defined.                         |
 +-----------+-------------------------------------------------------+
 | '8'       | 'saddle-stitch': Bind the Document(s) with one or     |
 |           | more staples (wire stitches) along the middle fold.   |
 |           | The exact number and placement of the staples and the |
 |           | middle fold are implementation defined and/or site    |
 |           | defined.                                              |

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 +-----------+-------------------------------------------------------+
 | '9'       | 'edge-stitch': Bind the Document(s) with one or more  |
 |           | staples (wire stitches) along one edge.  The exact    |
 |           | number and placement of the staples are               |
 |           | implementation defined and/or site defined.           |
 +-----------+-------------------------------------------------------+
 | '10'-'19' | reserved for future generic finishing enum values.    |
 +-----------+-------------------------------------------------------+
 | '20'      | 'staple-top-left': Bind the Document(s) with one or   |
 |           | more staples in the top left corner.                  |
 +-----------+-------------------------------------------------------+
 | '21'      | 'staple-bottom-left': Bind the Document(s) with one   |
 |           | or more staples in the bottom left corner.            |
 +-----------+-------------------------------------------------------+
 | '22'      | 'staple-top-right': Bind the Document(s) with one or  |
 |           | more staples in the top right corner.                 |
 +-----------+-------------------------------------------------------+
 | '23'      | 'staple-bottom-right': Bind the Document(s) with one  |
 |           | or more staples in the bottom right corner.           |
 +-----------+-------------------------------------------------------+
 | '24'      | 'edge-stitch-left': Bind the Document(s) with one or  |
 |           | more staples (wire stitches) along the left edge.     |
 |           | The exact number and placement of the staples are     |
 |           | implementation defined and/or site defined.           |
 +-----------+-------------------------------------------------------+
 | '25'      | 'edge-stitch-top': Bind the Document(s) with one or   |
 |           | more staples (wire stitches) along the top edge.  The |
 |           | exact number and placement of the staples are         |
 |           | implementation defined and/or site defined.           |
 +-----------+-------------------------------------------------------+
 | '26'      | 'edge-stitch-right': Bind the Document(s) with one or |
 |           | more staples (wire stitches) along the right edge.    |
 |           | The exact number and placement of the staples are     |
 |           | implementation defined and/or site defined.           |
 +-----------+-------------------------------------------------------+
 | '27'      | 'edge-stitch-bottom': Bind the Document(s) with one   |
 |           | or more staples (wire stitches) along the bottom      |
 |           | edge.  The exact number and placement of the staples  |
 |           | are implementation defined and/or site defined.       |
 +-----------+-------------------------------------------------------+
 | '28'      | 'staple-dual-left': Bind the Document(s) with two     |
 |           | staples (wire stitches) along the left edge, assuming |
 |           | a portrait Document (see above).                      |

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 +-----------+-------------------------------------------------------+
 | '29'      | 'staple-dual-top': Bind the Document(s) with two      |
 |           | staples (wire stitches) along the top edge, assuming  |
 |           | a portrait Document (see above).                      |
 +-----------+-------------------------------------------------------+
 | '30'      | 'staple-dual-right': Bind the Document(s) with two    |
 |           | staples (wire stitches) along the right edge,         |
 |           | assuming a portrait Document (see above).             |
 +-----------+-------------------------------------------------------+
 | '31'      | 'staple-dual-bottom': Bind the Document(s) with two   |
 |           | staples (wire stitches) along the bottom edge,        |
 |           | assuming a portrait Document (see above).             |
 +-----------+-------------------------------------------------------+
                  Table 10: "finishings" Enum Values

5.2.7. page-ranges (1setOf rangeOfInteger(1:MAX))

 This RECOMMENDED attribute identifies the range(s) of Input Pages
 that the Printer uses for each Set to be printed prior to imposition
 of those pages onto Impressions.  Nothing is printed for any pages
 identified that do not exist in the Set/Document(s).  Ranges MUST be
 in ascending order (1-3, 5-7, 15-19, etc.) and MUST NOT overlap so
 that a non-spooling Printer can process the Job in a single pass.  If
 the ranges are not ascending or are overlapping, the Printer MUST
 reject the request and return the 'client-error-bad-request'
 status-code.  The attribute is associated with Input Pages and not
 application-numbered pages such as the page numbers found in the
 headers and/or footers for certain word processing applications.
 For Jobs with multiple Documents, the "multiple-document-handling"
 attribute determines what constitutes a Set for purposes of the
 specified page range(s).  When "multiple-document-handling" is
 'single-document', the Printer MUST apply each supplied page range
 once to the concatenation of the Input Pages.  For example, if there
 are 8 Documents of 10 pages each, the page range '41-60' prints the
 pages in the 5th and 6th Documents as a single Document, and none of
 the pages of the other Documents are printed.  When
 "multiple-document-handling" is
 'separate-documents-uncollated-copies' or
 'separate-documents-collated-copies', the Printer MUST apply each
 supplied page range repeatedly to each Document copy.  For the same
 Job, the page range '1-3, 10-10' would print the first 3 pages
 and the 10th page of each of the 8 Documents in the Job, as 8
 separate Sets.

Sweet & McDonald Standards Track [Page 118] RFC 8011 IPP/1.1: Model and Semantics January 2017

 "page-ranges-supported" is a boolean value indicating whether the
 Printer is capable of supporting the printing of page ranges.  This
 capability can differ from one PDL to another.  There is no
 "page-ranges-default" attribute.  If the "page-ranges" attribute is
 not supplied by the Client, all pages of the Document are printed.
 Note: In many cases, the Client supplies only those Input Pages that
 need to be printed in the Document data, and the "page-ranges" Job
 Template attribute is not used.  However, Clients that submit
 already-generated Document data (either static content from some web
 site or previously submitted content the End User wishes to reprint)
 can use this attribute to print just a subset of the pages contained
 in the Document.  In this case, if a "page-ranges" value of 'n-m' is
 specified, the first page to be printed will be page n.  All
 subsequent pages of the Document will be printed through and
 including page m.
 Note: The effect of this attribute on Jobs with multiple Documents is
 controlled by the "multiple-document-handling" Job attribute
 (Section 5.2.4).  The relationship of this attribute and the other
 attributes that control Document processing is described in
 Appendix C.3.

5.2.8. sides (type2 keyword)

 This RECOMMENDED attribute specifies how Impressions are placed upon
 the sides of a Media Sheet.
 The standard 'keyword' values are:
 o  'one-sided': imposes each consecutive Impression upon the same
    side of consecutive Media Sheets.
 o  'two-sided-long-edge': imposes each consecutive pair of
    Impressions upon front and back sides of consecutive Media Sheets,
    such that the orientation of each pair of Impressions on the
    medium would be correct for the reader as if for binding on the
    long edge.  This imposition is sometimes called 'duplex' or
    'head-to-head'.
 o  'two-sided-short-edge': imposes each consecutive pair of
    Impressions upon front and back sides of consecutive Media Sheets,
    such that the orientation of each pair of Impressions on the
    medium would be correct for the reader as if for binding on the
    short edge.  This imposition is sometimes called 'tumble' or
    'head-to-toe'.

Sweet & McDonald Standards Track [Page 119] RFC 8011 IPP/1.1: Model and Semantics January 2017

 Note: The effect of this attribute on Jobs with multiple Documents is
 controlled by the "multiple-document-handling" Job attribute
 (Section 5.2.4).  The relationship of this attribute and the other
 attributes that control Document processing is described in
 Appendix C.3.

5.2.9. number-up (integer(1:MAX))

 This attribute specifies the number of Input Pages to impose upon a
 single Impression.  For example, if the value is:
 o  '1': the Printer MUST place one Input Page on a single Impression.
 o  '2': the Printer MUST place two Input Pages on a single
    Impression.
 o  '4': the Printer MUST place four Input Pages on a single
    Impression.
 In all cases, the Printer MAY add some sort of translation, scaling,
 or rotation of Input Pages when imposing them.
 Note: The effect of this attribute on Jobs with multiple Documents is
 controlled by the "multiple-document-handling" Job attribute
 (Section 5.2.4).  The relationship of this attribute and the other
 attributes that control Document processing is described in
 Appendix C.3.

5.2.10. orientation-requested (type2 enum)

 This RECOMMENDED attribute indicates the desired orientation for
 printed Input Pages; it does not describe the orientation of the
 Client-supplied Input Pages.
 For some Document formats (such as 'application/postscript'), the
 desired orientation of the Input Pages is sometimes specified within
 the Document data.  This information is generated by a Printer driver
 prior to the submission of the Print Job.  Other Document formats
 such as 'text/plain' do not include the notion of desired orientation
 within the Document data.  In the latter case, it is possible for the
 Printer to bind the desired orientation to the Document data after it
 has been submitted.  Printers MAY only support
 "orientation-requested" for some Document formats (e.g., 'text/plain'
 or 'text/html') but not others (e.g., 'application/postscript').
 This is no different than any other Job Template attribute, since
 Section 5.2, item 1, points out that a Printer can support or not
 support any Job Template attribute based on the Document format

Sweet & McDonald Standards Track [Page 120] RFC 8011 IPP/1.1: Model and Semantics January 2017

 supplied by the Client.  However, a special mention is made here,
 since it is very likely that a Printer will support
 "orientation-requested" for only a subset of the supported Document
 formats.
 Standard enum values are listed in Table 11.
 Note: The effect of this attribute on Jobs with multiple Documents is
 controlled by the "multiple-document-handling" Job attribute
 (Section 5.2.4).  The relationship of this attribute and the other
 attributes that control Document processing is described in
 Appendix C.3.

Sweet & McDonald Standards Track [Page 121] RFC 8011 IPP/1.1: Model and Semantics January 2017

 +-------+-----------------------------------------------------------+
 | Value | Symbolic Name and Description                             |
 +-------+-----------------------------------------------------------+
 | '3'   | 'portrait': The content will be imaged across the short   |
 |       | edge of the medium.                                       |
 +-------+-----------------------------------------------------------+
 | '4'   | 'landscape': The content will be imaged across the long   |
 |       | edge of the medium.  Landscape is defined to be a         |
 |       | rotation of the Input Page to be imaged by +90 degrees    |
 |       | with respect to the medium (i.e., counterclockwise) from  |
 |       | the portrait orientation.  Note: The +90 direction was    |
 |       | chosen because simple finishing on the long edge is the   |
 |       | same edge whether portrait or landscape.                  |
 +-------+-----------------------------------------------------------+
 | '5'   | 'reverse-landscape': The content will be imaged across    |
 |       | the long edge of the medium.  Reverse-landscape is        |
 |       | defined to be a rotation of the Input Page to be imaged   |
 |       | by -90 degrees with respect to the medium (i.e.,          |
 |       | clockwise) from the portrait orientation.  Note: The      |
 |       | 'reverse-landscape' value was added because some          |
 |       | applications rotate landscape -90 degrees from portrait,  |
 |       | rather than +90 degrees.                                  |
 +-------+-----------------------------------------------------------+
 | '6'   | 'reverse-portrait': The content will be imaged across the |
 |       | short edge of the medium.  Reverse-portrait is defined to |
 |       | be a rotation of the Input Page to be imaged by 180       |
 |       | degrees with respect to the medium from the portrait      |
 |       | orientation.  Note: The 'reverse-portrait' value was      |
 |       | added for use with the "finishings" attribute in cases    |
 |       | where the opposite edge is desired for finishing a        |
 |       | portrait Document on simple finishing devices that have   |
 |       | only one finishing position.  Thus, a 'text'/plain'       |
 |       | portrait Document can be stapled "on the right" by a      |
 |       | simple finishing device, as is common use with some       |
 |       | Middle Eastern languages such as Hebrew.                  |
 +-------+-----------------------------------------------------------+
             Table 11: "orientation-requested" Enum Values

Sweet & McDonald Standards Track [Page 122] RFC 8011 IPP/1.1: Model and Semantics January 2017

5.2.11. media (type2 keyword | name(MAX))

 This RECOMMENDED attribute identifies the medium that the Printer
 uses for all Impressions of the Job.
 The values for "media" historically have included medium names,
 medium sizes, input trays, and electronic forms so that one attribute
 specifies the media.  However, the Client SHOULD only use the media
 attribute to specify medium sizes using PWG Media Standardized Names
 [PWG5101.1].
 If a Printer supports a medium name as a value of this attribute,
 such a medium name implicitly selects an input tray that contains the
 specified medium.  If a Printer supports a medium size as a value of
 this attribute, such a medium size implicitly selects a medium name
 that in turn implicitly selects an input tray that contains the
 medium with the specified size.  If a Printer supports an input tray
 as the value of this attribute, such an input tray implicitly selects
 the medium that is in that input tray at the time the Job prints.
 This case includes manual-feed input trays.  If a Printer supports an
 electronic form as the value of this attribute, such an electronic
 form implicitly selects a medium name that in turn implicitly selects
 an input tray that contains the medium specified by the electronic
 form.  The electronic form also implicitly selects an image that the
 Printer MUST merge with the Document data as it prints each page.
 PWG Media Standardized Names [PWG5101.1] SHOULD be used.  Legacy
 'keyword' values are taken from ISO DPA [ISO10175], the Printer MIB
 [RFC3805], and ASME-Y14.1M [ASME-Y14.1M].  An Administrator MAY
 define additional values using the 'name' or 'keyword' attribute
 syntax, depending on implementation.
 There is also an additional Printer attribute named "media-ready",
 which differs from "media-supported" in that legal values only
 include the subset of "media-supported" values that are physically
 loaded and ready for printing with no Operator intervention required.
 The relationship of this attribute and the other attributes that
 control Document processing is described in Appendix C.3.
 Note: If supported by the Printer, Clients MAY use the alternative
 "media-col" attribute [PWG5100.3] [PWG5100.13] to specify medium
 requirements in greater detail.

Sweet & McDonald Standards Track [Page 123] RFC 8011 IPP/1.1: Model and Semantics January 2017

5.2.12. printer-resolution (resolution)

 This RECOMMENDED attribute identifies the output resolution that the
 Printer uses for the Job.
 Note: This attribute and the "print-quality" attribute
 (Section 5.2.13) are both used to specify the overall output quality
 of the Job.  If a Client specifies conflicting "printer-resolution"
 and "print-quality" values, Printers SHOULD use the "print-quality"
 value.

5.2.13. print-quality (type2 enum)

 This RECOMMENDED attribute specifies the print quality that the
 Printer uses for the Job.
 The standard enum values are listed in Table 12.
 Note: This attribute and the "printer-resolution" attribute
 (Section 5.2.12) are both used to specify the overall output quality
 of the Job.  If a Client specifies conflicting "printer-resolution"
 and "print-quality" values, Printers SHOULD use the "print-quality"
 value.
  +-------+---------------------------------------------------------+
  | Value | Symbolic Name and Description                           |
  +-------+---------------------------------------------------------+
  | '3'   | 'draft': lowest quality available on the Printer        |
  +-------+---------------------------------------------------------+
  | '4'   | 'normal': normal or intermediate quality on the Printer |
  +-------+---------------------------------------------------------+
  | '5'   | 'high': highest quality available on the Printer        |
  +-------+---------------------------------------------------------+
                 Table 12: "print-quality" Enum Values

5.3. Job Description and Status Attributes

 The attributes in this section form the attribute group called
 "job-description".  Tables 13 and 14 summarize these attributes.  The
 third column of each table indicates whether the attribute is a
 REQUIRED attribute that MUST be supported by Printers.  If it is not
 indicated as REQUIRED, then it is OPTIONAL.  The maximum size in
 octets for 'text' and 'name' attributes is indicated in parentheses.

Sweet & McDonald Standards Track [Page 124] RFC 8011 IPP/1.1: Model and Semantics January 2017

           +------------------+----------------+-----------+
           | Attribute        | Syntax         | REQUIRED? |
           +------------------+----------------+-----------+
           | job-impressions  | integer(0:MAX) |           |
           +------------------+----------------+-----------+
           | job-k-octets     | integer(0:MAX) |           |
           +------------------+----------------+-----------+
           | job-media-sheets | integer(1:MAX) |           |
           +------------------+----------------+-----------+
           | job-name         | name(MAX)      | REQUIRED  |
           +------------------+----------------+-----------+
           Table 13: Job Description Attributes (READ-WRITE)
 +-----------------------------+-------------------------+-----------+
 | Attribute                   | Syntax                  | REQUIRED? |
 +-----------------------------+-------------------------+-----------+
 | attributes-charset          | charset                 | REQUIRED  |
 +-----------------------------+-------------------------+-----------+
 | attributes-natural-language | naturalLanguage         | REQUIRED  |
 +-----------------------------+-------------------------+-----------+
 | date-time-at-completed      | dateTime|unknown|no-    |           |
 |                             | value                   |           |
 +-----------------------------+-------------------------+-----------+
 | date-time-at-creation       | dateTime|unknown        |           |
 +-----------------------------+-------------------------+-----------+
 | date-time-at-processing     | dateTime|unknown|no-    |           |
 |                             | value                   |           |
 +-----------------------------+-------------------------+-----------+
 | job-detailed-status-        | 1setOf text(MAX)        |           |
 | messages                    |                         |           |
 +-----------------------------+-------------------------+-----------+
 | job-document-access-errors  | 1setOf text(MAX)        |           |
 +-----------------------------+-------------------------+-----------+
 | job-id                      | integer(1:MAX)          | REQUIRED  |
 +-----------------------------+-------------------------+-----------+
 | job-impressions-completed   | integer(0:MAX)          |           |
 +-----------------------------+-------------------------+-----------+
 | job-k-octets-processed      | integer(0:MAX)          |           |
 +-----------------------------+-------------------------+-----------+
 | job-media-sheets-completed  | integer(0:MAX)          |           |
 +-----------------------------+-------------------------+-----------+
 | job-message-from-operator   | text(127)               |           |
 +-----------------------------+-------------------------+-----------+
 | job-more-info               | uri                     |           |
 +-----------------------------+-------------------------+-----------+
 | job-originating-user-name   | name(MAX)               | REQUIRED  |

Sweet & McDonald Standards Track [Page 125] RFC 8011 IPP/1.1: Model and Semantics January 2017

 +-----------------------------+-------------------------+-----------+
 | job-printer-up-time         | integer(1:MAX)          | REQUIRED  |
 +-----------------------------+-------------------------+-----------+
 | job-printer-uri             | uri                     | REQUIRED  |
 +-----------------------------+-------------------------+-----------+
 | job-state                   | type1 enum              | REQUIRED  |
 +-----------------------------+-------------------------+-----------+
 | job-state-message           | text(MAX)               |           |
 +-----------------------------+-------------------------+-----------+
 | job-state-reasons           | 1setOf type2 keyword    | REQUIRED  |
 +-----------------------------+-------------------------+-----------+
 | job-uri                     | uri                     | REQUIRED  |
 +-----------------------------+-------------------------+-----------+
 | number-of-documents         | integer(0:MAX)          |           |
 +-----------------------------+-------------------------+-----------+
 | number-of-intervening-jobs  | integer(0:MAX)          |           |
 +-----------------------------+-------------------------+-----------+
 | output-device-assigned      | name(127)               |           |
 +-----------------------------+-------------------------+-----------+
 | time-at-completed           | integer(MIN:MAX)        | REQUIRED  |
 +-----------------------------+-------------------------+-----------+
 | time-at-creation            | integer(MIN:MAX)        | REQUIRED  |
 +-----------------------------+-------------------------+-----------+
 | time-at-processing          | integer(MIN:MAX)        | REQUIRED  |
 +-----------------------------+-------------------------+-----------+
              Table 14: Job Status Attributes (READ-ONLY)

5.3.1. job-id (integer(1:MAX))

 This REQUIRED attribute contains the ID of the Job.  The Printer, on
 receipt of a new Job, generates an ID that identifies the new Job on
 that Printer.  The Printer returns the value of the "job-id"
 attribute as part of the response to a Job Creation request.
 For a description of this attribute and its relationship to the
 "job-uri" and "job-printer-uri" attributes, see the discussion in
 Section 3.4 ("Object Identity").

5.3.2. job-uri (uri)

 This REQUIRED attribute contains the URI for the Job.  The Printer,
 on receipt of a new Job, generates a URI that identifies the new Job.
 The Printer returns the value of the "job-uri" attribute as part of
 the response to a Job Creation request.  The precise format of a Job
 URI is implementation dependent [RFC3510] [RFC7472].  If the Printer
 supports more than one URI and there is some relationship between the
 newly formed Job URI and the Printer's URI, the Printer uses the

Sweet & McDonald Standards Track [Page 126] RFC 8011 IPP/1.1: Model and Semantics January 2017

 Printer URI supplied by the Client in the Job Creation request.  For
 example, if the Job Creation request comes in over a secure channel,
 the new Job URI MUST use the same secure channel.  This can be
 guaranteed because the Printer is responsible for generating the Job
 URI and the Printer is aware of its security configuration and policy
 as well as the Printer URI used in the Job Creation request.
 For a description of this attribute and its relationship to the
 "job-id" and "job-printer-uri" attributes, see the discussion in
 Section 3.4 ("Object Identity").

5.3.3. job-printer-uri (uri)

 This REQUIRED attribute identifies the Printer that created this Job.
 When a Printer creates a Job, it populates this attribute with the
 Printer URI that was used in the Job Creation request.  This
 attribute permits a Client to identify the Printer that created this
 Job when only the Job's URI is available to the Client.  The Client
 queries the creating Printer to determine which languages, charsets,
 and operations are supported for this Job.
 For a description of this attribute and its relationship to the
 "job-uri" and "job-id" attributes, see the discussion in Section 3.4
 ("Object Identity").

5.3.4. job-more-info (uri)

 Similar to "printer-more-info", this attribute contains the URI
 referencing some resource with more information about this Job,
 perhaps an HTML page containing status information about the Job.

5.3.5. job-name (name(MAX))

 This REQUIRED attribute is the name of the Job.  It is a name that is
 more user friendly than the "job-uri" or "job-id" attribute values.
 It does not need to be unique between Jobs.  The Job's "job-name"
 attribute is set to the value supplied by the Client in the
 "job-name" operation attribute in the Job Creation request (see
 Section 4.2.1.1).  If, however, the "job-name" operation attribute is
 not supplied by the Client in the Job Creation request, the Printer,
 on creation of the Job, MUST generate a name.  The Printer SHOULD
 generate the value of the Job's "job-name" attribute from the first
 of the following sources that produces a value: (1) the
 "document-name" operation attribute of the first (or only) Document,
 (2) the "document-URI" attribute of the first (or only) Document, or
 (3) any other piece of Job-specific and/or Document data.

Sweet & McDonald Standards Track [Page 127] RFC 8011 IPP/1.1: Model and Semantics January 2017

5.3.6. job-originating-user-name (name(MAX))

 This REQUIRED attribute contains the name of the End User that
 submitted the Print Job.  The Printer sets this attribute to the most
 authenticated printable name that it can obtain from the
 authentication service over which the IPP operation was received.
 Only if such a name is not available does the Printer use the value
 supplied by the Client in the "requesting-user-name" operation
 attribute of the Job Creation request (see Sections 5.4.2, 5.4.3,
 and 9).
 Note: The Printer needs to keep an internal originating user ID of
 some form, typically as a credential of a principal, with the Job.
 Since such an internal attribute is implementation dependent and not
 of interest to Clients, it is not specified as a Job attribute.  This
 originating user ID is used for authorization checks (if any) on all
 subsequent operations.

5.3.7. job-state (type1 enum)

 This REQUIRED attribute identifies the current state of the Job.
 Even though IPP defines seven values for Job states (plus the
 out-of-band 'unknown' value -- see Section 5.1), implementations only
 need to support those states that are appropriate for the particular
 implementation.  In other words, a Printer supports only those Job
 states implemented by the Output Device and available to the Printer
 implementation.
 Standard enum values are listed in Table 15.
 The final value for this attribute MUST be one of the following --
 'completed', 'canceled', or 'aborted' -- before the Printer removes
 the Job altogether.  The length of time that Jobs remain in the
 'canceled', 'aborted', and 'completed' states depends on
 implementation.  See Section 5.3.7.2.

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 Figure 3 shows the normal Job state transitions.  Normally, a Job
 progresses from left to right.  Other state transitions are unlikely
 but are not forbidden.  Not shown are the transitions to the
 'canceled' state from the 'pending', 'pending-held', and
 'processing-stopped' states.
                                                    +----> canceled
                                                   /
     +----> pending  -------> processing ---------+------> completed
     |         ^                   ^               \
 --->+         |                   |                +----> aborted
     |         v                   v               /
     +----> pending-held    processing-stopped ---+
                     Figure 3: IPP Job Life Cycle
 Jobs reach one of the three terminal states -- 'completed',
 'canceled', or 'aborted' -- after the Jobs have completed all
 activity, including stacking output media, and all Job Status
 attributes have reached their final values for the Job.

Sweet & McDonald Standards Track [Page 129] RFC 8011 IPP/1.1: Model and Semantics January 2017

 +--------+----------------------------------------------------------+
 | Values | Symbolic Name and Description                            |
 +--------+----------------------------------------------------------+
 | '3'    | 'pending': The Job is a candidate to start processing    |
 |        | but is not yet processing.                               |
 +--------+----------------------------------------------------------+
 | '4'    | 'pending-held': The Job is not a candidate for           |
 |        | processing for any number of reasons but will return to  |
 |        | the 'pending' state as soon as the reasons are no longer |
 |        | present.  The Job's "job-state-reasons" attribute MUST   |
 |        | indicate why the Job is no longer a candidate for        |
 |        | processing.                                              |
 +--------+----------------------------------------------------------+
 | '5'    | 'processing': One or more of the following: (1) the Job  |
 |        | is using, or is attempting to use, one or more purely    |
 |        | software processes that are analyzing, creating, or      |
 |        | interpreting a PDL, etc.; (2) the Job is using, or is    |
 |        | attempting to use, one or more hardware devices that are |
 |        | interpreting a PDL; making marks on a medium; and/or     |
 |        | performing finishing, such as stapling, etc.; (3) the    |
 |        | Printer has made the Job ready for printing, but the     |
 |        | Output Device is not yet printing it, either because the |
 |        | Job hasn't reached the Output Device or because the Job  |
 |        | is queued in the Output Device or some other spooler,    |
 |        | waiting for the Output Device to print it.  When the Job |
 |        | is in the 'processing' state, the entire Job state       |
 |        | includes the detailed status represented in the          |
 |        | Printer's "printer-state", "printer-state-reasons", and  |
 |        | "printer-state-message" attributes.  Implementations MAY |
 |        | include additional values in the Job's "job-state-       |
 |        | reasons" attribute to indicate the progress of the Job,  |
 |        | such as adding the 'job-printing' value to indicate when |
 |        | the Output Device is actually making marks on paper      |
 |        | and/or the 'processing-to-stop-point' value to indicate  |
 |        | that the Printer is in the process of canceling or       |
 |        | aborting the Job.                                        |

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 +--------+----------------------------------------------------------+
 | '6'    | 'processing-stopped': The Job has stopped while          |
 |        | processing for any number of reasons and will return to  |
 |        | the 'processing' state as soon as the reasons are no     |
 |        | longer present.  The Job's "job-state-reasons" attribute |
 |        | MAY indicate why the Job has stopped processing.  For    |
 |        | example, if the Output Device is stopped, the 'printer-  |
 |        | stopped' value MAY be included in the Job's "job-state-  |
 |        | reasons" attribute.  Note: When an Output Device is      |
 |        | stopped, the device usually indicates its condition in   |
 |        | human-readable form locally at the device.  A Client can |
 |        | obtain more complete device status remotely by querying  |
 |        | the Printer's "printer-state", "printer-state-reasons",  |
 |        | and "printer-state-message" attributes.                  |
 +--------+----------------------------------------------------------+
 | '7'    | 'canceled':  The Job has been canceled by a Cancel-Job   |
 |        | operation, and the Printer has completed canceling the   |
 |        | Job.  All Job Status attributes have reached their final |
 |        | values for the Job.  While the Printer is canceling the  |
 |        | Job, the Job remains in its current state, but the Job's |
 |        | "job-state-reasons" attribute SHOULD contain the         |
 |        | 'processing-to-stop-point' value and one of the          |
 |        | 'canceled-by-user', 'canceled-by-operator', or           |
 |        | 'canceled-at-device' values.  When the Job moves to the  |
 |        | 'canceled' state, the 'processing-to-stop-point' value,  |
 |        | if present, MUST be removed, but 'canceled-by-xxx', if   |
 |        | present, MUST remain.                                    |
 +--------+----------------------------------------------------------+
 | '8'    | 'aborted': The Job has been aborted by the system,       |
 |        | usually while the Job was in the 'processing' or         |
 |        | 'processing-stopped' state, and the Printer has          |
 |        | completed aborting the Job; all Job Status attributes    |
 |        | have reached their final values for the Job.  While the  |
 |        | Printer is aborting the Job, the Job remains in its      |
 |        | current state, but the Job's "job-state-reasons"         |
 |        | attribute SHOULD contain the 'processing-to-stop-point'  |
 |        | and 'aborted-by-system' values.  When the Job moves to   |
 |        | the 'aborted' state, the 'processing-to-stop-point'      |
 |        | value, if present, MUST be removed, but the 'aborted-by- |
 |        | system' value, if present, MUST remain.                  |

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 +--------+----------------------------------------------------------+
 | '9'    | 'completed': The Job has completed successfully or with  |
 |        | warnings or errors after processing, all of the Job      |
 |        | Media Sheets have been successfully stacked in the       |
 |        | appropriate output bin(s), and all Job Status attributes |
 |        | have reached their final values for the Job.  The Job's  |
 |        | "job-state-reasons" attribute SHOULD contain one of the  |
 |        | 'completed-successfully', 'completed-with-warnings', or  |
 |        | 'completed-with-errors' values.                          |
 +--------+----------------------------------------------------------+
                   Table 15: "job-state" Enum Values

5.3.7.1. Forwarding Servers

 As with all other IPP attributes, if the implementation cannot
 determine the correct value for this attribute, it SHOULD respond
 with the out-of-band 'unknown' value (see Section 5.1) rather than
 try to guess at some possibly incorrect value and confuse the
 End User about the state of the Job.  For example, if the
 implementation is just a gateway into some printing system from which
 it can normally get status, but temporarily is unable, then the
 implementation should return the 'unknown' value.  However, if the
 implementation is a gateway to a printing system that never provides
 detailed status about the Print Job, the implementation MAY set the
 IPP Job's state to 'completed', provided that it also sets the
 'queued-in-device' value in the Job's "job-state-reasons" attribute
 (see Section 5.3.8).

5.3.7.2. Partitioning of Job States

 This section describes the partitioning of the seven Job states into
 phases: Job Not Completed, Job Retention, Job History, and Job
 Removal.  This section also explains the 'job-restartable' value of
 the "job-state-reasons" Job Status attribute for use with the
 Restart-Job and Resubmit-Job [PWG5100.11] operations.
 Job Not Completed: When a Job is in the 'pending', 'pending-held',
 'processing', or 'processing-stopped' state, the Job is not
 completed.
 Job Retention: When a Job enters one of the three terminal Job states
 -- 'completed', 'canceled', or 'aborted' -- the IPP Printer MAY
 "retain" the Job in a restartable condition for an implementation-
 defined time period.  This time period MAY be zero seconds and MAY
 depend on the terminal Job state.  This phase is called "Job
 Retention".  While in the Job Retention phase, the Job's Document
 data is retained and a Client can restart the Job using the

Sweet & McDonald Standards Track [Page 132] RFC 8011 IPP/1.1: Model and Semantics January 2017

 Restart-Job operation.  If the Printer supports the Restart-Job or
 Resubmit-Job operation, then it SHOULD indicate that the Job is
 restartable by adding the 'job-restartable' value to the Job's
 "job-state-reasons" attribute (see Section 5.3.8) during the Job
 Retention phase.
 Job History: After the Job Retention phase expires for a Job, the
 Printer deletes the Document data for the Job and the Job becomes
 part of the Job History.  The Printer MAY also delete any number of
 the Job attributes.  Since the Job is no longer restartable, the
 Printer MUST remove the 'job-restartable' value from the Job's
 "job-state-reasons" attribute, if present.  Printers SHOULD keep the
 Job in the Job History phase for at least 60 seconds to allow Clients
 to discover the final disposition of the Job.
 Job Removal: After the Job has remained in the Job History for an
 implementation-defined time, such as when the number of Jobs exceeds
 a fixed number or after a fixed time period (which MAY be
 zero seconds), the IPP Printer removes the Job from the system.
 Using the Get-Jobs operation and supplying the 'not-completed' value
 for the "which-jobs" operation attribute, a Client is requesting Jobs
 in the Job Not Completed phase.  Using the Get-Jobs operation and
 supplying the 'completed' value for the "which-jobs" operation
 attribute, a Client is requesting Jobs in the Job Retention and Job
 History phases.  Using the Get-Job-Attributes operation, a Client is
 requesting a Job in any phase except Job Removal.  After Job Removal,
 the Get-Job-Attributes and Get-Jobs operations no longer are capable
 of returning any information about a Job.

5.3.8. job-state-reasons (1setOf type2 keyword)

 This REQUIRED attribute provides additional information about the
 Job's current state, i.e., information that augments the value of the
 Job's "job-state" attribute.
 These values MAY be used with any Job state or states for which the
 reason makes sense.  Some of these value definitions indicate
 conformance requirements; the rest are OPTIONAL.  Furthermore, when
 implemented, the Printer MUST return these values when the reason
 applies and MUST NOT return them when the reason no longer applies,
 whether the value of the Job's "job-state" attribute changed or not.
 When the Job does not have any reasons for being in its current
 state, the value of the Job's "job-state-reasons" attribute MUST be
 'none'.

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 Note: While values cannot be added to the "job-state" attribute
 without impacting deployed Clients that take actions upon receiving
 "job-state" values, it is the intent that additional
 "job-state-reasons" values can be defined and registered without
 impacting such deployed Clients.  In other words, the
 "job-state-reasons" attribute is intended to be extensible.
 The following standard 'keyword' values are defined.  For ease of
 understanding, the values are presented in the order in which the
 reasons are likely to occur (if implemented):
 o  'none': There are no reasons for the Job's current state.  This
    state reason is semantically equivalent to "job-state-reasons"
    without any value and MUST be used when there is no other value,
    since the '1setOf' attribute syntax requires at least one value.
 o  'job-incoming': Either (1) the Printer has accepted the Create-Job
    operation and is expecting additional Send-Document and/or
    Send-URI operations or (2) the Printer is retrieving/accepting
    Document data as a result of a Print-Job, Print-URI,
    Send-Document, or Send-URI operation.
 o  'job-data-insufficient': The Create-Job operation has been
    accepted by the Printer, but the Printer is expecting additional
    Document data before it can move the Job into the 'processing'
    state.  If a Printer starts processing before it has received all
    data, the Printer removes the 'job-data-insufficient' reason, but
    the 'job-incoming' reason remains.  If a Printer starts processing
    after it has received all data, the Printer removes the
    'job-data-insufficient' reason and the 'job-incoming' reason at
    the same time.
 o  'document-access-error': After accepting a Print-URI or Send-URI
    request, the Printer could not access one or more Documents passed
    by reference.  This reason is intended to cover any file access
    problem, including 'file does not exist' and 'access denied'
    because of an access control problem.  The Printer MAY also
    indicate the Document access error using the
    "job-document-access-errors" Job Status attribute (see
    Section 5.3.11).  The Printer can (1) abort the Job and move the
    Job to the 'aborted' Job state or (2) print all Documents that are
    accessible and move the Job to the 'completed' Job state with the
    'completed-with-errors' value in the Job's "job-state-reasons"
    attribute.  This value SHOULD be supported if the Print-URI or
    Send-URI operations are supported.

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 o  'submission-interrupted': The Job was not completely submitted for
    some unforeseen reason, such as (1) the Printer has crashed before
    the Job was closed by the Client, (2) the Printer or the Document
    transfer method has crashed in some non-recoverable way before the
    Document data was entirely transferred to the Printer, or (3) the
    Client crashed or failed to close the Job before the time-out
    period.  See Section 5.4.31.
 o  'job-outgoing': The Printer is transmitting the Job to the Output
    Device.
 o  'job-hold-until-specified': The value of the Job's
    "job-hold-until" attribute was specified with a time period that
    is still in the future.  The Job MUST NOT be a candidate for
    processing until this reason is removed and there are no other
    reasons to hold the Job.  This value SHOULD be supported if the
    "job-hold-until" Job Template attribute is supported.
 o  'resources-are-not-ready': At least one of the resources needed by
    the Job, such as media, fonts, resource objects, etc., is not
    ready on any of the physical Output Devices for which the Job is a
    candidate.  This condition MAY be detected when the Job is
    accepted, or subsequently while the Job is pending or processing,
    depending on implementation.  The Job can remain in its current
    state or be moved to the 'pending-held' state, depending on
    implementation and/or Job scheduling policy.
 o  'printer-stopped-partly': The value of the Printer's
    "printer-state-reasons" attribute contains the value
    'stopped-partly'.
 o  'printer-stopped': The value of the Printer's "printer-state"
    attribute is 'stopped'.
 o  'job-interpreting': The Job is in the 'processing' state, but,
    more specifically, the Printer is interpreting the Document data.
 o  'job-queued': The Job is in the 'processing' state, but, more
    specifically, the Printer has queued the Document data.
 o  'job-transforming': The Job is in the 'processing' state, but,
    more specifically, the Printer is interpreting Document data and
    producing another electronic representation.
 o  'job-queued-for-marker': The Job is in any of the 'pending-held',
    'pending', or 'processing' states, but, more specifically, the
    Printer has completed enough processing of the Document to be able
    to start marking, and the Job is waiting for the marker.  Systems

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    that require human intervention to release Jobs using the
    Release-Job operation put the Job into the 'pending-held' Job
    state.  Systems that automatically select a Job to use the marker
    put the Job into the 'pending' Job state or keep the Job in the
    'processing' Job state while waiting for the marker, depending on
    implementation.  All implementations put the Job into the
    'processing' state when marking does begin.
 o  'job-printing': The Output Device is marking media.  This value is
    useful for Printers that spend a great deal of time processing
    (1) when no marking is happening and they want to show that
    marking is now happening or (2) when the Job is in the process of
    being canceled or aborted while the Job remains in the
    'processing' state, but the marking has not yet stopped so that
    Impression or sheet counts are still increasing for the Job.
 o  'job-canceled-by-user': The Job was canceled by the owner of the
    Job using the Cancel-Job request, i.e., by a user whose
    authenticated identity is the same as the value of the originating
    user that created the Job, or by some other authorized End User,
    such as a member of the Job owner's security group.  This value
    SHOULD be supported.
 o  'job-canceled-by-operator': The Job was canceled by the Operator
    using the Cancel-Job request, i.e., by a user who has been
    authenticated as having Operator privileges (whether local or
    remote).  If the security policy is to allow anyone to cancel
    anyone's Job, then this value can be used when the Job is canceled
    by other than the owner of the Job.  For such a security policy,
    in effect, everyone is an Operator as far as canceling Jobs with
    IPP is concerned.  This value SHOULD be supported if the
    implementation permits canceling by other than the owner of
    the Job.
 o  'job-canceled-at-device': The Job was canceled by an unidentified
    local user, i.e., a user at a console at the device.  This value
    SHOULD be supported if the implementation supports canceling Jobs
    at the console.
 o  'aborted-by-system': The Job (1) is in the process of being
    aborted, (2) has been aborted by the system and placed in the
    'aborted' state, or (3) has been aborted by the system and placed
    in the 'pending-held' state, so that a user or Operator can
    manually try the Job again.  This value SHOULD be supported.

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 o  'unsupported-compression': The Job was aborted by the system
    because the Printer determined, while attempting to decompress the
    Document data, that the compression algorithm is actually not
    among those supported by the Printer.  This value MUST be
    supported, since "compression" is a REQUIRED operation attribute.
 o  'compression-error': The Job was aborted by the system because the
    Printer encountered an error in the Document data while
    decompressing it.  If the Printer posts this reason, the Document
    data has already passed any tests that would have led to the
    'unsupported-compression' "job-state-reasons" value.
 o  'unsupported-document-format': The Job was aborted by the system
    because the Document data's "document-format" attribute is not
    among those supported by the Printer.  If the Client specifies
    "document-format" as 'application/octet-stream', the Printer MAY
    abort the Job and post this reason even though the
    "document-format" value is among the values of the Printer's
    "document-format-supported" Printer attribute but not among the
    auto-sensed Document formats.  This value MUST be supported, since
    "document-format" is a REQUIRED operation attribute.
 o  'document-format-error': The Job was aborted by the system because
    the Printer encountered an error in the Document data while
    processing it.  If the Printer posts this reason, the Document
    data has already passed any tests that would have led to the
    'unsupported-document-format' "job-state-reasons" value.
 o  'processing-to-stop-point': The requester has issued a Cancel-Job
    operation or the Printer has aborted the Job, but the Printer is
    still performing some actions on the Job until a specified stop
    point occurs or Job termination/cleanup is completed.
    If the implementation requires some measurable time to cancel the
    Job in the 'processing' or 'processing-stopped' Job state, the
    Printer MUST use this value to indicate that the Printer is still
    performing some actions on the Job while the Job remains in the
    'processing' or 'processing-stopped' state.  Once at the stop
    point, the Printer moves the Job from the 'processing' state to
    the 'canceled' or 'aborted' Job state.
 o  'service-off-line': The Printer is offline and accepting no Jobs.
    All 'pending' Jobs are put into the 'pending-held' state.  This
    situation could be true if the service's or Document transform's
    input is impaired or broken.
 o  'job-completed-successfully': The Job completed successfully.
    This value SHOULD be supported.

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 o  'job-completed-with-warnings': The Job completed with warnings.
    This value SHOULD be supported if the implementation detects
    warnings.
 o  'job-completed-with-errors': The Job completed with errors (and
    possibly warnings too).  This value SHOULD be supported if the
    implementation detects errors.
 o  'job-restartable': This Job is retained (see Section 5.3.7.2) and
    is currently able to be restarted using the Restart-Job (see
    Section 4.3.7) or Resubmit-Job [PWG5100.11] operation.  If
    'job-restartable' is a value of the Job's "job-state-reasons"
    attribute, then the Printer MUST accept a Restart-Job operation
    for that Job.  This value SHOULD be supported if the Restart-Job
    operation is supported.
 o  'queued-in-device': The Job has been forwarded to a device or
    print system that is unable to send back status.  The Printer sets
    the Job's "job-state" attribute to 'completed' and adds the
    'queued-in-device' value to the Job's "job-state-reasons"
    attribute to indicate that the Printer has no additional
    information about the Job and never will have any better
    information.  See Section 5.3.7.1.

5.3.9. job-state-message (text(MAX))

 This RECOMMENDED attribute specifies information about the
 "job-state" and "job-state-reasons" attributes in human-readable
 text.  If the Printer supports this attribute, the Printer MUST be
 able to generate this message in any of the natural languages
 identified by the Printer's "generated-natural-language-supported"
 attribute (see the "attributes-natural-language" operation attribute
 specified in Section 4.1.4.1).
 The value SHOULD NOT contain additional information not contained in
 the values of the "job-state" and "job-state-reasons" attributes,
 such as interpreter error information.  Otherwise, application
 programs might attempt to parse the (localized) text.  For such
 additional information, such as interpreter errors for application
 program consumption or specific Document access errors, new
 attributes with 'keyword' values need to be developed and registered.

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5.3.10. job-detailed-status-messages (1setOf text(MAX))

 This attribute specifies additional detailed and technical
 information about the Job.  The Printer SHOULD localize the message,
 unless such localization would obscure the technical meaning of the
 message.  Clients MUST NOT attempt to parse the value of this
 attribute.  See "job-document-access-errors" (Section 5.3.11) for
 additional errors that a program can process.

5.3.11. job-document-access-errors (1setOf text(MAX))

 This attribute provides additional information about each Document
 access error for this Job encountered by the Printer after it
 returned a response to the Print-URI or Send-URI operation and
 subsequently attempted to access document(s) supplied in the
 Print-URI or Send-URI operation.  For errors in the protocol that is
 identified by the URI scheme in the "document-uri" operation
 attribute, such as 'http:' or 'ftp:', the error code is returned in
 parentheses, followed by the URI.  For example:
 (404) http://www.example.com/filename.pdf
 Most Internet protocols use decimal error codes (unlike IPP), so the
 ASCII error code representation is in decimal.

5.3.12. number-of-documents (integer(0:MAX))

 This attribute indicates the number of Documents in the Job, i.e.,
 the number of Send-Document, Send-URI, Print-Job, or Print-URI
 operations that the Printer has accepted for this Job, regardless of
 whether the Document data has reached the Printer.
 Implementations supporting the RECOMMENDED Create-Job/Send-Document/
 Send-URI operations SHOULD support this attribute so that Clients can
 query the number of Documents in each Job.

5.3.13. output-device-assigned (name(127))

 This attribute identifies the Output Device to which the Printer has
 assigned this Job.  If an Output Device implements an embedded
 Printer, the Printer SHOULD set this attribute.  If a print server
 implements a Printer, the value MAY be empty (zero-length string) or
 not returned until the Printer assigns an Output Device to the Job.
 This attribute is particularly useful when a single Printer supports
 multiple devices (so-called "fan-out" -- see Section 3.1).

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5.3.14. Event Time Job Status Attributes

 This section defines the Job Status attributes that indicate the time
 at which certain events occur for a Job.  If the Job event has not
 yet occurred, then the Printer MUST return the 'no-value' out-of-band
 value (see the beginning of Section 5.1).  The
 "time-at-xxx (integer)" attributes represent time as an 'integer'
 representing the number of seconds since the device was powered up
 (informally called "time ticks").  The "date-time-at-xxx (dateTime)"
 attributes represent time as 'dateTime' representing date and time
 (including an offset from UTC).
 In order to populate these attributes, the Printer copies the
 value(s) of the following Printer Status attributes at the time the
 event occurs:
 1.  the value in the Printer's "printer-up-time" attribute for the
     "time-at-xxx (integer)" attributes.
 2.  the value in the Printer's "printer-current-time" attribute for
     the "date-time-at-xxx (dateTime)" attributes.
 If the Printer resets its "printer-up-time" attribute to 1 on
 power-up (see Section 5.4.29) and has persistent Jobs, then it MUST
 change all of those Jobs' "time-at-xxx (integer)" (time tick) Job
 attributes whose events have occurred either to:
 1.  0 to indicate that the event happened before the most recent
     power-up, or
 2.  the negative of the number of seconds before the most recent
     power-up that the event took place, if the Printer knows the
     exact number of seconds.
 If a Client queries a "time-at-xxx (integer)" time tick Job attribute
 and finds the value to be 0 or negative, the Client MUST assume that
 the event occurred in some life other than the Printer's current
 life.
 Note: A Printer does not change the values of any
 "date-time-at-xxx (dateTime)" Job attributes on power-up.

5.3.14.1. time-at-creation (integer(MIN:MAX))

 This REQUIRED attribute indicates the time at which the Job was
 created.

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5.3.14.2. time-at-processing (integer(MIN:MAX))

 This REQUIRED attribute indicates the time at which the Job first
 began processing after the Job Creation request or the most recent
 Restart-Job operation.  The out-of-band 'no-value' value is returned
 if the Job has not yet been in the 'processing' state (see the
 beginning of Section 5.1).

5.3.14.3. time-at-completed (integer(MIN:MAX))

 This REQUIRED attribute indicates the time at which the Job entered a
 Terminating State ('completed', 'canceled', or 'aborted').  The
 out-of-band 'no-value' value is returned if the Job has not yet
 completed, been canceled, or aborted (see the beginning of
 Section 5.1).

5.3.14.4. job-printer-up-time (integer(1:MAX))

 This REQUIRED Job Status attribute indicates the amount of time (in
 seconds) that the Printer implementation has been up and running.
 This attribute is an alias for the "printer-up-time" Printer Status
 attribute (see Section 5.4.29).
 A Client MAY request this attribute in a Get-Job-Attributes or
 Get-Jobs request and use the value returned in combination with other
 requested Event Time Job Status attributes in order to display time
 attributes to a user.  The difference between this attribute and the
 'integer' value of a "time-at-xxx" attribute is the number of seconds
 ago that the "time-at-xxx" event occurred.  A Client can compute the
 wall-clock time at which the "time-at-xxx" event occurred by
 subtracting this difference from the Client's wall-clock time.

5.3.14.5. date-time-at-creation (dateTime|unknown)

 This RECOMMENDED attribute indicates the date and time at which the
 Job was created.

5.3.14.6. date-time-at-processing (dateTime|unknown|no-value)

 This RECOMMENDED attribute indicates the date and time at which the
 Job first began processing after the Job Creation request or the most
 recent Restart-Job operation.

5.3.14.7. date-time-at-completed (dateTime|unknown|no-value)

 This RECOMMENDED attribute indicates the date and time at which the
 Job entered a Terminating State ('completed', 'canceled', or
 'aborted').

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5.3.15. number-of-intervening-jobs (integer(0:MAX))

 This attribute indicates the number of Jobs that are "ahead" of this
 Job in the relative chronological order of expected time to complete
 (i.e., the current scheduled order).  For efficiency, it is only
 necessary to calculate this value when an operation is performed that
 requests this attribute.

5.3.16. job-message-from-operator (text(127))

 This attribute provides a message from an Operator, Administrator, or
 "intelligent" process to indicate to the End User the reasons for
 modification or other management action taken on a Job.

5.3.17. Job Size Attributes

 This subsection defines Job attributes that describe the size of the
 Job.  These attributes are not intended to be counters; they are
 intended to be useful routing and scheduling information if known.
 For these attributes, the Printer can try to compute the value if it
 is not supplied in the Job Creation request.  Even if the Client does
 supply a value for these three attributes in the Job Creation
 request, the Printer MAY choose to change the value if the Printer is
 able to compute a value that is more accurate than the
 Client-supplied value.  The Printer can determine the correct value
 for these attributes either right at Job submission time or at any
 later point in time.

5.3.17.1. job-k-octets (integer(0:MAX))

 This attribute specifies the total size of the Document(s) in
 K octets, i.e., in units of 1024 octets requested to be processed
 in the Job.  The value MUST be rounded up, so that a Job between
 1 and 1024 octets MUST be indicated as being 1, 1025 to 2048 MUST
 be 2, etc.
 This value MUST NOT include the multiplicative factors contributed by
 the number of copies specified by the "copies" attribute, independent
 of whether the device can process multiple copies without making
 multiple passes over the Job or Document data and independent of
 whether the output is collated or not.  Thus, the value is
 independent of the implementation and indicates the size of the
 Document(s) measured in K octets independent of the number of copies.

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 This value also MUST NOT include the multiplicative factor due to a
 copies instruction embedded in the Document data.  If the Document
 data actually includes replications of the Document data, this value
 will include such replication.  In other words, this value is always
 the size of the source Document data, rather than a measure of the
 hardcopy output to be produced.

5.3.17.2. job-impressions (integer(0:MAX))

 This RECOMMENDED attribute specifies the total size in number of
 Impressions of the Document(s) being submitted (see the definition of
 "Impression" in Section 2.3.4).
 As with "job-k-octets", this value MUST NOT include the
 multiplicative factors contributed by the number of copies specified
 by the "copies" attribute, independent of whether the device can
 process multiple copies without making multiple passes over the Job
 or Document data and independent of whether the output is collated or
 not.  Thus, the value is independent of the implementation and
 reflects the size of the Document(s) measured in Impressions
 independent of the number of copies.
 As with "job-k-octets", this value also MUST NOT include the
 multiplicative factor due to a copies instruction embedded in the
 Document data.  If the Document data actually includes replications
 of the Document data, this value will include such replication.  In
 other words, this value is always the number of Impressions in the
 source Document data, rather than a measure of the number of
 Impressions to be produced by the Job.

5.3.17.3. job-media-sheets (integer(1:MAX))

 This RECOMMENDED attribute specifies the total number of Media Sheets
 to be produced for this Job.
 Unlike the "job-k-octets" and the "job-impressions" attributes, this
 value MUST include the multiplicative factors contributed by the
 number of copies specified by the "copies" attribute and a 'number of
 copies' instruction embedded in the Document data, if any.  This
 difference allows the Administrator to control the lower and upper
 bounds of both (1) the size of the Document(s) with
 "job-k-octets-supported" and "job-impressions-supported" and
 (2) the size of the Job with "job-media-sheets-supported".

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5.3.18. Job Progress Attributes

 This subsection defines Job attributes that describe the progress of
 the Job.  These attributes are intended to be counters.  That is, the
 values for a Job that has not started processing MUST be 0.  When the
 Job's "job-state" is 'processing' or 'processing-stopped', this value
 is intended to contain the amount of the Job that has been processed
 to the time at which the attributes are requested.  When the Job
 enters the 'completed', 'canceled', or 'aborted' states, these values
 are the final values for the Job.

5.3.18.1. job-k-octets-processed (integer(0:MAX))

 This attribute specifies the total number of octets processed in
 K octets, i.e., in units of 1024 octets so far.  The value MUST be
 rounded up, so that a Job between 1 and 1024 octets inclusive MUST be
 indicated as being 1, 1025 to 2048 inclusive MUST be 2, etc.
 For implementations where multiple copies are produced by the
 interpreter with only a single pass over the data, the final value
 MUST be equal to the value of the "job-k-octets" attribute.  For
 implementations where multiple copies are produced by the interpreter
 by processing the data for each copy, the final value MUST be a
 multiple of the value of the "job-k-octets" attribute.

5.3.18.2. job-impressions-completed (integer(0:MAX))

 This RECOMMENDED attribute specifies the number of Impressions
 completed for the Job so far.  For printing devices, the Impressions
 completed includes interpreting, marking, and stacking the output.

5.3.18.3. job-media-sheets-completed (integer(0:MAX))

 This RECOMMENDED Job attribute specifies the number of Media Sheets
 that have been marked and stacked for the entire Job so far, whether
 those sheets have been processed on one side or on both.

5.3.19. attributes-charset (charset)

 This REQUIRED attribute is populated using the value in the
 Client-supplied "attributes-charset" attribute in the Job Creation
 request.  It identifies the charset (coded character set and encoding
 method) used by any Job attributes with attribute syntaxes 'text' and
 'name' that were supplied by the Client in the Job Creation request.
 See Section 4.1.4 for a complete description of the
 "attributes-charset" operation attribute.

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 This attribute does not indicate the charset in which the 'text' and
 'name' values are stored internally in the Job.  The internal charset
 is implementation defined.  The Printer MUST convert from whatever
 the internal charset is to that being requested in an operation as
 specified in Section 4.1.4.

5.3.20. attributes-natural-language (naturalLanguage)

 This REQUIRED attribute is populated using the value in the
 Client-supplied "attributes-natural-language" attribute in the Job
 Creation request.  It identifies the natural language used for any
 Job attributes with attribute syntaxes 'text' and 'name' that were
 supplied by the Client in the Job Creation request.  See
 Section 4.1.4 for a complete description of the
 "attributes-natural-language" operation attribute.  See
 Sections 5.1.2.2 and 5.1.3.2 for how a Natural Language Override can
 be supplied explicitly for each 'text' and 'name' attribute value
 that differs from the value identified by the
 "attributes-natural-language" attribute.

5.4. Printer Description and Status Attributes

 These attributes form the attribute group called
 "printer-description".  Tables 16 and 17 summarize these attributes,
 their syntax, and whether they are REQUIRED for a Printer to support.
 If they are not indicated as REQUIRED, they are OPTIONAL.  The
 maximum size in octets for 'text' and 'name' attributes is indicated
 in parentheses.
 Note: How these attributes are set by an Administrator is outside the
 scope of this document.
 +-----------------------------+-----------------------+-------------+
 | Attribute                   | Syntax                | REQUIRED?   |
 +-----------------------------+-----------------------+-------------+
 | charset-configured          | charset               | REQUIRED    |
 +-----------------------------+-----------------------+-------------+
 | charset-supported           | 1setOf charset        | REQUIRED    |
 +-----------------------------+-----------------------+-------------+
 | color-supported             | boolean               | RECOMMENDED |
 +-----------------------------+-----------------------+-------------+
 | compression-supported       | 1setOf type2 keyword  | REQUIRED    |
 +-----------------------------+-----------------------+-------------+
 | document-format-default     | mimeMediaType         | REQUIRED    |
 +-----------------------------+-----------------------+-------------+
 | document-format-supported   | 1setOf mimeMediaType  | REQUIRED    |

Sweet & McDonald Standards Track [Page 145] RFC 8011 IPP/1.1: Model and Semantics January 2017

 +-----------------------------+-----------------------+-------------+
 | generated-natural-language- | 1setOf                | REQUIRED    |
 | supported                   | naturalLanguage       |             |
 +-----------------------------+-----------------------+-------------+
 | ipp-versions-supported      | 1setOf type2 keyword  | REQUIRED    |
 +-----------------------------+-----------------------+-------------+
 | job-impressions-supported   | rangeOfInteger(0:MAX) | RECOMMENDED |
 +-----------------------------+-----------------------+-------------+
 | job-k-octets-supported      | rangeOfInteger(0:MAX) |             |
 +-----------------------------+-----------------------+-------------+
 | job-media-sheets-supported  | rangeOfInteger(1:MAX) |             |
 +-----------------------------+-----------------------+-------------+
 | multiple-document-jobs-     | boolean               | RECOMMENDED |
 | supported                   |                       |             |
 +-----------------------------+-----------------------+-------------+
 | multiple-operation-time-out | integer(1:MAX)        | RECOMMENDED |
 +-----------------------------+-----------------------+-------------+
 | natural-language-configured | naturalLanguage       | REQUIRED    |
 +-----------------------------+-----------------------+-------------+
 | operations-supported        | 1setOf type2 enum     | REQUIRED    |
 +-----------------------------+-----------------------+-------------+
 | pdl-override-supported      | type2 keyword         | REQUIRED    |
 +-----------------------------+-----------------------+-------------+
 | printer-driver-installer    | uri                   |             |
 +-----------------------------+-----------------------+-------------+
 | printer-info                | text(127)             | RECOMMENDED |
 +-----------------------------+-----------------------+-------------+
 | printer-location            | text(127)             | RECOMMENDED |
 +-----------------------------+-----------------------+-------------+
 | printer-make-and-model      | text(127)             | RECOMMENDED |
 +-----------------------------+-----------------------+-------------+
 | printer-message-from-       | text(127)             |             |
 | operator                    |                       |             |
 +-----------------------------+-----------------------+-------------+
 | printer-more-info-          | uri                   |             |
 | manufacturer                |                       |             |
 +-----------------------------+-----------------------+-------------+
 | printer-name                | name(127)             | REQUIRED    |
 +-----------------------------+-----------------------+-------------+
 | reference-uri-schemes-      | 1setOf uriScheme      |             |
 | supported                   |                       |             |
 +-----------------------------+-----------------------+-------------+
         Table 16: Printer Description Attributes (READ-WRITE)

Sweet & McDonald Standards Track [Page 146] RFC 8011 IPP/1.1: Model and Semantics January 2017

 +------------------------------+----------------------+-------------+
 | Attribute                    | Syntax               | REQUIRED?   |
 +------------------------------+----------------------+-------------+
 | pages-per-minute-color       | integer(0:MAX)       | RECOMMENDED |
 +------------------------------+----------------------+-------------+
 | pages-per-minute             | integer(0:MAX)       | RECOMMENDED |
 +------------------------------+----------------------+-------------+
 | printer-current-time         | dateTime|unknown     | RECOMMENDED |
 +------------------------------+----------------------+-------------+
 | printer-is-accepting-jobs    | boolean              | REQUIRED    |
 +------------------------------+----------------------+-------------+
 | printer-more-info            | uri                  | RECOMMENDED |
 +------------------------------+----------------------+-------------+
 | printer-state                | type1 enum           | REQUIRED    |
 +------------------------------+----------------------+-------------+
 | printer-state-message        | text(MAX)            | RECOMMENDED |
 +------------------------------+----------------------+-------------+
 | printer-state-reasons        | 1setOf type2 keyword | REQUIRED    |
 +------------------------------+----------------------+-------------+
 | printer-up-time              | integer(1:MAX)       | REQUIRED    |
 +------------------------------+----------------------+-------------+
 | printer-uri-supported        | 1setOf uri           | REQUIRED    |
 +------------------------------+----------------------+-------------+
 | queued-job-count             | integer(0:MAX)       | REQUIRED    |
 +------------------------------+----------------------+-------------+
 | uri-authentication-supported | 1setOf type2 keyword | REQUIRED    |
 +------------------------------+----------------------+-------------+
 | uri-security-supported       | 1setOf type2 keyword | REQUIRED    |
 +------------------------------+----------------------+-------------+
            Table 17: Printer Status Attributes (READ-ONLY)

5.4.1. printer-uri-supported (1setOf uri)

 This REQUIRED Printer attribute contains one or more URIs for the
 Printer.  It MAY contain more than one URI for the Printer.  An
 Administrator determines a Printer's URIs and configures this
 attribute to contain those URIs by some means outside the scope of
 this IPP/1.1 document.  The precise format of the URIs is
 implementation dependent and depends on the protocol.  See
 Sections 5.4.2 and 5.4.3 for a description of the
 "uri-authentication-supported" and "uri-security-supported"
 attributes, both of which are the REQUIRED companion attributes to
 this "printer-uri-supported" attribute.  See Sections 3.4 ("Object
 Identity") and 9.2 ("URIs in Operation, Job, and Printer Attributes")
 for more information.

Sweet & McDonald Standards Track [Page 147] RFC 8011 IPP/1.1: Model and Semantics January 2017

5.4.2. uri-authentication-supported (1setOf type2 keyword)

 This REQUIRED Printer attribute MUST have the same cardinality
 (contain the same number of values) as the "printer-uri-supported"
 attribute.  This attribute identifies the Client Authentication
 mechanism associated with each URI listed in the
 "printer-uri-supported" attribute.  The Printer uses the specified
 mechanism to identify the authenticated user (see Section 9.3).  The
 "i-th" value in "uri-authentication-supported" corresponds to the
 "i-th" value in "printer-uri-supported", and it describes the
 authentication mechanisms used by the Printer when accessed via that
 URI.  See [RFC8010] for more details on Client Authentication.
 The following standard 'keyword' values are defined:
 o  'none': There is no authentication mechanism associated with the
    URI.  The Printer assumes that the authenticated user is
    'anonymous'.
 o  'requesting-user-name': When a Client performs an operation whose
    target is the associated URI, the Printer assumes that the
    authenticated user is specified by the "requesting-user-name"
    operation attribute (see Section 9.3).  If the
    "requesting-user-name" attribute is absent in a request, the
    Printer assumes that the authenticated user is 'anonymous'.
 o  'basic': When a Client performs an operation whose target is the
    associated URI, the Printer challenges the Client with HTTP Basic
    authentication [RFC7617].  The Printer assumes that the
    authenticated user is the name received via the Basic
    authentication mechanism.
 o  'digest': When a Client performs an operation whose target is the
    associated URI, the Printer challenges the Client with HTTP Digest
    authentication [RFC7616].  The Printer assumes that the
    authenticated user is the name received via the Digest
    authentication mechanism.
 o  'certificate': When a Client performs an operation whose target is
    the associated URI, the Printer expects the Client to provide an
    X.509 certificate.  The Printer assumes that the authenticated
    user is one of the textual names (Common Name or Subject Alternate
    Names) contained within the certificate.

Sweet & McDonald Standards Track [Page 148] RFC 8011 IPP/1.1: Model and Semantics January 2017

5.4.3. uri-security-supported (1setOf type2 keyword)

 This REQUIRED Printer attribute MUST have the same cardinality
 (contain the same number of values) as the "printer-uri-supported"
 attribute.  This attribute identifies the security mechanisms used
 for each URI listed in the "printer-uri-supported" attribute.  The
 "i-th" value in "uri-security-supported" corresponds to the "i-th"
 value in "printer-uri-supported", and it describes the security
 mechanisms used for accessing the Printer via that URI.  See
 [RFC8010] for more details on security mechanisms.
 The following standard 'keyword' values are defined:
 o  'none': There are no secure communication channel protocols in use
    for the given URI.
 o  'tls': TLS [RFC5246] [RFC7525] is the secure communications
    channel protocol in use for the given URI.
 This attribute is orthogonal to the definition of a Client
 Authentication mechanism.  Specifically, 'none' does not exclude
 Client Authentication.  See Section 5.4.2.
 Consider the following example.  For a single Printer, an
 Administrator configures the "printer-uri-supported",
 "uri-authentication-supported", and "uri-security-supported"
 attributes as follows:
    "printer-uri-supported": 'ipp://printer.example.com/ipp/print/
    open-use-printer', 'ipp://printer.example.com/ipp/print/
    restricted-use-printer', 'ipps://printer.example.com/ipp/print/
    private-printer'
    "uri-authentication-supported": 'none', 'digest', 'basic'
    "uri-security-supported": 'none', 'none', 'tls'
 In this case, one Printer has three URIs.
 o  For the first URI, 'ipp://printer.example.com/ipp/print/
    open-use-printer', the value 'none' in "uri-security-supported"
    indicates that there is no secure channel protocol configured to
    run under HTTP.  The value of 'none' in
    "uri-authentication-supported" indicates that all users are
    'anonymous'.  There will be no challenge, and the Printer will
    ignore "requesting-user-name".

Sweet & McDonald Standards Track [Page 149] RFC 8011 IPP/1.1: Model and Semantics January 2017

 o  For the second URI, 'ipp://printer.example.com/ipp/print/
    restricted-use-printer', the value 'none' in
    "uri-security-supported" indicates that there is no secure channel
    protocol configured to run under HTTP.  The value of 'digest' in
    "uri-authentication-supported" indicates that the Printer will
    issue a challenge and that the Printer will use the name supplied
    by the Digest mechanism to determine the authenticated user (see
    Section 9.3).
 o  For the third URI, 'ipps://printer.example.com/ipp/print/
    private-printer', the value 'tls' in "uri-security-supported"
    indicates that TLS is being used to secure the channel.  The
    Client SHOULD be prepared to use TLS framing to negotiate an
    acceptable ciphersuite to use while communicating with the
    Printer.  In this case, the name implies the use of a secure
    communications channel, but the fact is made explicit by the
    presence of the 'tls' value in "uri-security-supported".  The
    Client does not need to resort to understanding which security
    mechanisms it must use by following naming conventions or by
    parsing the URI to determine which security mechanisms are
    implied.  The value of 'basic' in "uri-authentication-supported"
    indicates that the Printer will issue a challenge and that the
    Printer will use the name supplied by the Basic mechanism to
    determine the authenticated user (see Section 9.3).  Because this
    challenge occurs in a TLS session, the channel is secure.
 Some Printers will be configured to support only one channel (either
 configured to use TLS access or not) and only one authentication
 mechanism.  Such Printers only have one URI listed in the
 "printer-uri-supported" attribute.  No matter the configuration of
 the Printer (whether it has only one URI or more than one URI), a
 Client MUST supply only one URI in the target "printer-uri" operation
 attribute.

5.4.4. printer-name (name(127))

 This REQUIRED Printer attribute contains the name of the Printer.  It
 is a name that is more End User friendly than a URI.  An
 Administrator determines a Printer's name and sets this attribute to
 that name.  This name can be the last part of the Printer's URI, or
 it can be unrelated.  In non-US-English locales, a name can contain
 characters that are not allowed in a URI.

5.4.5. printer-location (text(127))

 This RECOMMENDED Printer attribute identifies the location of the
 device.  This could include things like 'in Room 123A, second floor
 of building XYZ'.

Sweet & McDonald Standards Track [Page 150] RFC 8011 IPP/1.1: Model and Semantics January 2017

5.4.6. printer-info (text(127))

 This RECOMMENDED Printer attribute provides descriptive information
 about this Printer.  This could include things like 'This printer can
 be used for printing color transparencies for HR presentations', or
 'Out of courtesy for others, please print only small (1-5 page) jobs
 at this printer', or even 'This printer is going away on July 1;
 please find a new printer'.

5.4.7. printer-more-info (uri)

 This RECOMMENDED Printer attribute contains a URI used to obtain more
 information about this specific Printer.  For example, this could be
 an HTTP URI referencing an HTML page accessible to a web browser.
 The information obtained from this URI is intended for End User
 consumption.  Features outside the scope of IPP can be accessed from
 this URI.  The information is intended to be specific to this Printer
 instance and site-specific services, e.g., Job pricing, services
 offered, and End User assistance.  The device manufacturer can
 initially populate this attribute.

5.4.8. printer-driver-installer (uri)

 This Printer attribute contains a URI to use to locate the driver
 installer for this Printer.  This attribute is intended for
 consumption by automata.  The mechanics of Printer driver
 installation are outside the scope of this document.  The device
 manufacturer can initially populate this attribute.

5.4.9. printer-make-and-model (text(127))

 This RECOMMENDED Printer attribute identifies the make and model of
 the device.  The device manufacturer can initially populate this
 attribute.

5.4.10. printer-more-info-manufacturer (uri)

 This Printer attribute contains a URI used to obtain more information
 about this type of device.  The information obtained from this URI is
 intended for End User consumption.  Features outside the scope of IPP
 can be accessed from this URI (e.g., latest firmware, upgrades,
 Printer drivers, optional features available, details on color
 support).  The information is intended to be germane to this Printer
 without regard to site-specific modifications or services.  The
 device manufacturer can initially populate this attribute.

Sweet & McDonald Standards Track [Page 151] RFC 8011 IPP/1.1: Model and Semantics January 2017

5.4.11. printer-state (type1 enum)

 This REQUIRED Printer attribute identifies the current state of the
 device.  The "printer-state reasons" attribute augments the
 "printer-state" attribute to give more detailed information about the
 Printer in the given Printer state.
 A Printer updates this attribute continually if asynchronous event
 notification [RFC3995] is supported.
 Standard enum values are defined in Table 18.  Values of
 "printer-state-reasons", such as 'spool-area-full' and
 'stopped-partly', MAY be used to provide further information.
 +-------+-----------------------------------------------------------+
 | Value | Symbolic Name and Description                             |
 +-------+-----------------------------------------------------------+
 | '3'   | 'idle': Indicates that new Jobs can start processing      |
 |       | without waiting.                                          |
 +-------+-----------------------------------------------------------+
 | '4'   | 'processing': Indicates that Jobs are processing; new     |
 |       | Jobs will wait before processing.                         |
 +-------+-----------------------------------------------------------+
 | '5'   | 'stopped': Indicates that no Jobs can be processed and    |
 |       | intervention is required.                                 |
 +-------+-----------------------------------------------------------+
                 Table 18: "printer-state" Enum Values

5.4.12. printer-state-reasons (1setOf type2 keyword)

 This REQUIRED Printer attribute supplies additional detail about the
 device's state.  Some of the value definitions indicate conformance
 requirements; the rest are OPTIONAL.
 Each 'keyword' value MAY have a suffix to indicate its level of
 severity.  The three levels are 'report' (least severe), 'warning',
 and 'error' (most severe):
 o  '-report': This suffix indicates that the reason is a "report".
    An implementation can choose to omit some or all reports.  Some
    reports specify finer granularity about the Printer state; others
    serve as a precursor to a warning.  A report MUST contain nothing
    that could affect the printed output.  Reports correspond to the
    'other' value for the prtAlertSeverityLevel property in the
    Printer MIB [RFC3805].

Sweet & McDonald Standards Track [Page 152] RFC 8011 IPP/1.1: Model and Semantics January 2017

 o  '-warning': This suffix indicates that the reason is a "warning".
    An implementation can choose to omit some or all warnings.
    Warnings serve as a precursor to an error.  A warning MUST contain
    nothing that prevents a Job from completing, though in some cases
    the output can be of lower quality.  Warnings correspond to the
    'warning' value for the prtAlertSeverityLevel property in the
    Printer MIB [RFC3805].
 o  '-error': This suffix indicates that the reason is an "error".  An
    implementation MUST include all errors.  If this attribute
    contains one or more errors, the Printer MUST be in the 'stopped'
    state.  Errors correspond to the 'critical' value for the
    prtAlertSeverityLevel property in the Printer MIB [RFC3805].
 If the implementation does not add any one of the three suffixes and
 the value is not 'none', Clients can assume that the reason is an
 "error" if the Printer is in the 'stopped' state and a "warning" if
 the Printer is in any other state.
 If a Printer controls more than one Output Device, each value of this
 attribute MAY apply to one or more of the Output Devices.  An error
 on one Output Device that does not stop the Printer as a whole MAY
 appear as a warning in the Printer's "printer-state-reasons"
 attribute.  If "printer-state" for such a Printer has a value of
 'stopped', then there MUST be an error reason among the values in the
 "printer-state-reasons" attribute.
 The following standard 'keyword' values are defined:
 o  'none': There are no reasons.  This state reason is semantically
    equivalent to "printer-state-reasons" without any value and MUST
    be used, since the '1setOf' attribute syntax requires at least one
    value.
 o  'other': The device has detected a condition other than one listed
    in this document.
 o  'connecting-to-device': The Printer has scheduled a Job on the
    Output Device and is in the process of connecting to a shared
    network Output Device (and might not be able to actually start
    printing the Job for an arbitrarily long time, depending on the
    usage of the Output Device by other servers on the network).
 o  'cover-open': One or more covers on the device are open,
    equivalent to a prtCoverStatus [RFC3805] of 3 (coverOpen).
 o  'developer-empty: The device is out of developer.

Sweet & McDonald Standards Track [Page 153] RFC 8011 IPP/1.1: Model and Semantics January 2017

 o  'developer-low': The device is low on developer.
 o  'door-open': One or more doors on the device are open, equivalent
    to a prtCoverStatus [RFC3805] of 3 (coverOpen).
 o  'fuser-over-temp': The fuser temperature is above normal,
    equivalent to a prtMarkerStatus [RFC3805] of 19 (the sum of
    "Unavailable because Broken" (3) and "Critical Alerts" (16)).
 o  'fuser-under-temp': The fuser temperature is below normal,
    equivalent to a prtMarkerStatus [RFC3805] of 19 (the sum of
    "Unavailable because Broken" (3) and "Critical Alerts" (16)).
 o  'input-tray-missing': One or more input trays are not in the
    device, equivalent to a prtInputStatus [RFC3805] of 19 (the sum of
    "Unavailable because Broken" (3) and "Critical Alerts" (16)).
 o  'interlock-open': One or more interlock devices on the Printer are
    unlocked, equivalent to a prtCoverStatus [RFC3805] of 5
    (interlockOpen).
 o  'interpreter-resource-unavailable': An interpreter resource is
    unavailable (i.e., font, form).
 o  'marker-supply-empty: The device is out of at least one marker
    supply, e.g., toner, ink, ribbon.
 o  'marker-supply-low': The device is low on at least one marker
    supply, e.g., toner, ink, ribbon.
 o  'marker-waste-almost-full': The device marker supply waste
    receptacle is almost full.
 o  'marker-waste-full': The device marker supply waste receptacle is
    full.
 o  'media-empty': At least one input tray is empty, equivalent to a
    prtInputStatus [RFC3805] of 19 (the sum of "Unavailable because
    Broken" (3) and "Critical Alerts" (16)).
 o  'media-jam': The device has a media jam, equivalent to a
    prtInputStatus [RFC3805] of 19 (the sum of "Unavailable because
    Broken" (3) and "Critical Alerts" (16)).
 o  'media-low': At least one input tray is low on media, equivalent
    to a prtInputStatus [RFC3805] of 8 (Non-Critical Alerts).

Sweet & McDonald Standards Track [Page 154] RFC 8011 IPP/1.1: Model and Semantics January 2017

 o  'media-needed': A tray has run out of media, equivalent to a
    prtInputStatus [RFC3805] value of 17 (the sum of "Unavailable and
    OnRequest" (1) and "Critical Alerts" (16)).
 o  'moving-to-paused': Someone has paused the Printer using the
    Pause-Printer operation (see Section 4.2.7) or other means, but
    the device(s) is taking an appreciable time to stop.  Later, when
    all output has stopped, "printer-state" becomes 'stopped', and the
    'paused' value replaces the 'moving-to-paused' value in the
    "printer-state-reasons" attribute.  This value MUST be supported
    if the Pause-Printer operation is supported and the implementation
    takes significant time to pause a device in certain circumstances.
 o  'opc-life-over': The optical photo conductor is no longer
    functioning, equivalent to a prtMarkerStatus [RFC3805] of 19
    (the sum of "Unavailable because Broken" (3) and
    "Critical Alerts" (16)).
 o  'opc-near-eol': The optical photo conductor is near its end of
    life, equivalent to a prtMarkerStatus [RFC3805] of 8 (Non-Critical
    Alerts).
 o  'output-area-almost-full': One or more output areas are almost
    full, e.g., tray, stacker, collator, equivalent to a
    prtOutputStatus [RFC3805] of 8 (Non-Critical Alerts).
 o  'output-area-full': One or more output areas are full, e.g., tray,
    stacker, collator, equivalent to a prtInputStatus [RFC3805] of 19
    (the sum of "Unavailable because Broken" (3) and
    "Critical Alerts" (16)).
 o  'output-tray-missing': One or more output trays are not in the
    device, equivalent to a prtOutputStatus [RFC3805] of 19 (the sum
    of "Unavailable because Broken" (3) and "Critical Alerts" (16)).
 o  'paused': Someone has paused the Printer using the Pause-Printer
    operation (see Section 4.2.7) or other means, and the Printer's
    "printer-state" is 'stopped'.  In this state, a Printer MUST NOT
    produce printed output, but it MUST perform other operations
    requested by a Client.  If a Printer had been printing a Job when
    the Printer was paused, the Printer MUST resume printing that Job
    when the Printer is no longer paused and leave no evidence in the
    printed output of such a pause.  This value MUST be supported if
    the Pause-Printer operation is supported.

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 o  'shutdown': Someone has removed a Printer from service, and the
    device can be powered down or physically removed.  In this state,
    a Printer MUST NOT produce printed output, and unless the Printer
    is realized by a print server that is still active, the Printer
    MUST perform no other operations requested by a Client, including
    returning this value.  If a Printer had been printing a Job when
    it was shut down, the Printer MAY resume printing that Job when
    the Printer is restarted.  If the Printer resumes printing such a
    Job, it can leave evidence in the printed output of such a
    shutdown, e.g., the part printed before the shutdown can be
    printed a second time after the shutdown.
 o  'spool-area-full': The limit of persistent storage allocated for
    spooling has been reached.  The Printer is temporarily unable to
    accept more Jobs.  The Printer will remove this value when it is
    able to accept more Jobs.  This value SHOULD be used by a
    non-spooling Printer that only accepts one or a small number of
    Jobs at a time or by a spooling Printer that has filled the spool
    space.
 o  'stopped-partly': When a Printer controls more than one Output
    Device, this reason indicates that one or more Output Devices are
    stopped.  If the reason is a report, fewer than half of the Output
    Devices are stopped.  If the reason is a warning, fewer than all
    of the Output Devices are stopped.
 o  'stopping': The Printer is in the process of stopping the device
    and will be stopped in a while.  When the device is stopped, the
    Printer will change the Printer's state to 'stopped'.  The
    'stopping-warning' reason is never an error, even for a Printer
    with a single Output Device.  When an Output Device ceases
    accepting Jobs, the Printer will have this reason while the Output
    Device completes printing.
 o  'timed-out': The server was able to connect to the Output Device
    (or is always connected) but was unable to get a response from the
    Output Device.
 o  'toner-empty': The device is out of toner.
 o  'toner-low': The device is low on toner.

Sweet & McDonald Standards Track [Page 156] RFC 8011 IPP/1.1: Model and Semantics January 2017

5.4.13. printer-state-message (text(MAX))

 This RECOMMENDED Printer attribute specifies information about the
 "printer-state" and "printer-state-reasons" attributes in human-
 readable text.  If the Printer supports this attribute, the Printer
 MUST be able to generate this message in any of the natural languages
 identified by the Printer's "generated-natural-language-supported"
 attribute (see the "attributes-natural-language" operation attribute
 specified in Section 4.1.4.1).

5.4.14. ipp-versions-supported (1setOf type2 keyword)

 This REQUIRED attribute identifies the IPP version(s) that this
 Printer supports, including major and minor versions, i.e., the
 version numbers for which this Printer implementation meets the
 conformance requirements.  For version number validation, the Printer
 matches the (2-octet binary) "version-number" parameter supplied by
 the Client in each request (see Sections 4.1.1 and 4.1.8) with the
 (US-ASCII) 'keyword' values of this attribute.
 The following standard 'keyword' values are defined in this document:
 o  '1.0': Meets the conformance requirements of IPP version 1.0 as
    specified in RFC 2566 [RFC2566] and RFC 2565 [RFC2565], including
    any extensions registered according to Section 7 and any extension
    defined in this version or any future version of the IPP Model and
    Semantics document (this document) or the IPP Encoding and
    Transport document [RFC8010] following the rules, if any, when the
    "version-number" parameter is '1.0'.
 o  '1.1': Meets the conformance requirements of IPP version 1.1 as
    specified in this document and [RFC8010], including any extensions
    registered according to Section 7 and any extension defined in any
    future versions of this document or [RFC8010] following the rules,
    if any, when the "version-number" parameter is '1.1'.
 Additional values are defined in "IPP Version 2.0, 2.1, and 2.2"
 [PWG5100.12].

5.4.15. operations-supported (1setOf type2 enum)

 This REQUIRED Printer attribute specifies the set of supported
 operations for this Printer and contained Jobs.
 This attribute is encoded as any other enum attribute syntax
 according to [RFC8010] as 32 bits.  However, all 32-bit enum values
 for this attribute MUST NOT exceed 0x00007fff, since these same
 values are also passed in two octets in the "operation-id" field (see

Sweet & McDonald Standards Track [Page 157] RFC 8011 IPP/1.1: Model and Semantics January 2017

 Section 4.1.1) in each Protocol request with the two high-order
 octets omitted in order to indicate the operation being performed
 [RFC8010].
 Table 19 lists the "operations-supported" attribute and
 "operation-id" parameter (see Section 4.1.2) enum values that are
 defined in this document.
 +---------------+---------------------------------------------------+
 | Value         | Operation Name                                    |
 +---------------+---------------------------------------------------+
 | 0x0000        | reserved, not used                                |
 +---------------+---------------------------------------------------+
 | 0x0001        | reserved, not used                                |
 +---------------+---------------------------------------------------+
 | 0x0002        | Print-Job                                         |
 +---------------+---------------------------------------------------+
 | 0x0003        | Print-URI                                         |
 +---------------+---------------------------------------------------+
 | 0x0004        | Validate-Job                                      |
 +---------------+---------------------------------------------------+
 | 0x0005        | Create-Job                                        |
 +---------------+---------------------------------------------------+
 | 0x0006        | Send-Document                                     |
 +---------------+---------------------------------------------------+
 | 0x0007        | Send-URI                                          |
 +---------------+---------------------------------------------------+
 | 0x0008        | Cancel-Job                                        |
 +---------------+---------------------------------------------------+
 | 0x0009        | Get-Job-Attributes                                |
 +---------------+---------------------------------------------------+
 | 0x000a        | Get-Jobs                                          |
 +---------------+---------------------------------------------------+
 | 0x000b        | Get-Printer-Attributes                            |
 +---------------+---------------------------------------------------+
 | 0x000c        | Hold-Job                                          |
 +---------------+---------------------------------------------------+
 | 0x000d        | Release-Job                                       |
 +---------------+---------------------------------------------------+
 | 0x000e        | Restart-Job                                       |
 +---------------+---------------------------------------------------+
 | 0x000f        | reserved for a future operation                   |

Sweet & McDonald Standards Track [Page 158] RFC 8011 IPP/1.1: Model and Semantics January 2017

 +---------------+---------------------------------------------------+
 | 0x0010        | Pause-Printer                                     |
 +---------------+---------------------------------------------------+
 | 0x0011        | Resume-Printer                                    |
 +---------------+---------------------------------------------------+
 | 0x0012        | Purge-Jobs                                        |
 +---------------+---------------------------------------------------+
 | 0x0013-0x3fff | additional registered operations (see the IANA    |
 |               | IPP registry and Section 7.8)                     |
 +---------------+---------------------------------------------------+
 | 0x4000-0x7fff | reserved for vendor extensions (see Section 7.8)  |
 +---------------+---------------------------------------------------+
             Table 19: "operations-supported" Enum Values

5.4.16. multiple-document-jobs-supported (boolean)

 This RECOMMENDED Printer attribute indicates whether the Printer
 supports more than one Document per Job, i.e., more than one
 Send-Document operation with Document data and/or Send-URI
 operations.  If the Printer supports the Create-Job and Send-Document
 operations (see Sections 4.2.4 and 4.3.1), it MUST support this
 attribute.

5.4.17. charset-configured (charset)

 This REQUIRED Printer attribute identifies the charset that the
 Printer has been configured to represent 'text' and 'name' Printer
 attributes that are set by the Operator, Administrator, or
 manufacturer, i.e., for "printer-name" (name), "printer-location"
 (text), "printer-info" (text), and "printer-make-and-model" (text).
 Therefore, the value of the Printer's "charset-configured" attribute
 MUST also be among the values of the Printer's "charset-supported"
 attribute.

5.4.18. charset-supported (1setOf charset)

 This REQUIRED Printer attribute identifies the set of charsets that
 the Printer and contained Jobs support in attributes with attribute
 syntaxes 'text' and 'name'.  At least the value 'utf-8' MUST be
 present, since IPP objects MUST support the UTF-8 [RFC3629] charset.
 If a Printer supports a charset, it means that for all attributes of
 syntaxes 'text' and 'name' the Printer MUST (1) accept the charset in
 requests and (2) return the charset in responses as needed.
 If more charsets than UTF-8 are supported, the Printer MUST perform
 charset conversion between the charsets as described in
 Section 4.1.4.2.

Sweet & McDonald Standards Track [Page 159] RFC 8011 IPP/1.1: Model and Semantics January 2017

5.4.19. natural-language-configured (naturalLanguage)

 This REQUIRED Printer attribute identifies the natural language that
 the Printer has been configured to represent 'text' and 'name'
 Printer attributes that are set by the Operator, Administrator, or
 manufacturer, i.e., for "printer-name" (name), "printer-location"
 (text), "printer-info" (text), and "printer-make-and-model" (text).
 When returning these Printer attributes, the Printer MAY return them
 in the configured natural language specified by this attribute,
 instead of the natural language requested by the Client in the
 "attributes-natural-language" operation attribute.  See
 Section 4.1.4.1 for the specification of the OPTIONAL support for
 multiple natural languages.  Therefore, the value of the Printer's
 "natural-language-configured" attribute MUST also be among the values
 of the Printer's "generated-natural-language-supported" attribute.

5.4.20. generated-natural-language-supported (1setOf naturalLanguage)

 This REQUIRED Printer attribute identifies the natural language(s)
 that the Printer and contained Jobs support in attributes with
 attribute syntaxes 'text' and 'name'.  The natural language(s)
 supported depends on implementation and/or configuration.  Unlike
 charsets, Printers MUST accept requests with any natural language or
 any Natural Language Override whether the natural language is
 supported or not.
 If a Printer supports a natural language, it means that for any of
 the attributes for which the Printer or Job generates messages, i.e.,
 for the "job-state-message" and "printer-state-message" attributes
 and operation messages (see Section 4.1.5) in operation responses,
 the Printer and Job MUST be able to generate messages in any of the
 Printer's supported natural languages.  See Sections 4.1.4, 5.1.2,
 and 5.1.3 for the definitions of 'text' and 'name' attributes in
 operation requests and responses.
 Note: A Printer that supports multiple natural languages often has
 separate catalogs of messages, one for each natural language
 supported.

5.4.21. document-format-default (mimeMediaType)

 This REQUIRED Printer attribute identifies the Document format that
 the Printer has been configured to assume if the Client does not
 supply a "document-format" operation attribute in any of the
 operation requests that supply Document data.  The standard values
 for this attribute are Internet media types (sometimes called "MIME
 media types").  For further details, see the description of the
 'mimeMediaType' attribute syntax in Section 5.1.10.

Sweet & McDonald Standards Track [Page 160] RFC 8011 IPP/1.1: Model and Semantics January 2017

5.4.22. document-format-supported (1setOf mimeMediaType)

 This REQUIRED Printer attribute identifies the set of Document
 formats that the Printer and contained Jobs can support.  For further
 details, see the description of the 'mimeMediaType' attribute syntax
 in Section 5.1.10.

5.4.23. printer-is-accepting-jobs (boolean)

 This REQUIRED Printer attribute indicates whether the Printer is
 currently able to accept Jobs, i.e., is accepting Print-Job,
 Print-URI, and Create-Job requests.  If the value is 'true', the
 Printer is accepting Jobs.  If the value is 'false', the Printer is
 currently rejecting any Jobs submitted to it.  In this case, the
 Printer returns the 'server-error-not-accepting-jobs' status-code.
 This value is independent of the "printer-state" and
 "printer-state-reasons" attributes because its value does not affect
 the current Job; rather, it affects future Jobs.  This attribute,
 when 'false', causes the Printer to reject Jobs even when
 "printer-state" is 'idle' or, when 'true', causes the Printer to
 accept Jobs even when "printer-state" is 'stopped'.

5.4.24. queued-job-count (integer(0:MAX))

 This REQUIRED Printer attribute contains a count of the number of
 Jobs that are either 'pending', 'processing', 'pending-held', or
 'processing-stopped' and is set by the Printer.

5.4.25. printer-message-from-operator (text(127))

 This Printer attribute provides a message from an Operator,
 Administrator, or "intelligent" process to indicate to the End User
 information or status of the Printer, such as why it is unavailable
 or when it is expected to be available.

5.4.26. color-supported (boolean)

 This RECOMMENDED Printer attribute identifies whether the device is
 capable of any type of color printing at all, including highlight
 color.  All Document instructions having to do with color are
 embedded within the Document PDL, although IPP attributes can affect
 the rendering of those colors.
 Note: End Users are able to determine the nature and details of the
 color support by querying the "printer-more-info-manufacturer"
 Printer attribute.

Sweet & McDonald Standards Track [Page 161] RFC 8011 IPP/1.1: Model and Semantics January 2017

5.4.27. reference-uri-schemes-supported (1setOf uriScheme)

 This Printer attribute specifies which URI schemes are supported for
 use in the "document-uri" operation attribute of the Print-URI or
 Send-URI operations.  If a Printer supports these OPTIONAL
 operations, it MUST support the "reference-uri-schemes-supported"
 Printer attribute with at least the following URI scheme value:
 o  'ftp': The Printer will use an FTP 'get' operation as defined in
    [RFC959] using FTP URLs as defined by [RFC3986].
 The Printer MAY support other URI schemes (see Section 5.1.7).

5.4.28. pdl-override-supported (type2 keyword)

 This REQUIRED Printer attribute expresses the ability of a particular
 Printer implementation to override Document data instructions with
 IPP attributes.  The following 'keyword' values are defined in this
 document:
 o  'attempted': This value indicates that the Printer attempts to
    make the IPP attribute values take precedence over embedded
    instructions in the Document data; however, there is no guarantee.
 o  'not-attempted': This value indicates that the Printer makes no
    attempt to make the IPP attribute values take precedence over
    embedded instructions in the Document data.
 Appendix C contains a full description of how this attribute
 interacts with and affects other IPP attributes, especially the
 "ipp-attribute-fidelity" attribute.

5.4.29. printer-up-time (integer(1:MAX))

 This REQUIRED Printer attribute indicates the amount of time (in
 seconds) that this Printer instance has been up and running.  The
 value is a monotonically increasing value starting from 1 when the
 Printer is started up (initialized, booted, etc.).  This value is
 used to populate the Event Time Job Status attributes
 "time-at-creation", "time-at-processing", and "time-at-completed"
 (see Section 5.3.14).

Sweet & McDonald Standards Track [Page 162] RFC 8011 IPP/1.1: Model and Semantics January 2017

 If the Printer goes down at some value 'n' and comes back up, the
 implementation MAY:
 1.  know how long it has been down and resume at some value greater
     than 'n', or
 2.  restart from 1.
 In other words, if the device or devices that the Printer is
 representing are restarted or power-cycled, the Printer MAY continue
 counting this value or MAY reset this value to 1, depending on
 implementation.  However, if the Printer software ceases running and
 restarts without knowing the last value for "printer-up-time", the
 implementation MUST reset this value to 1.  If this value is reset
 and the Printer has persistent Jobs, the Printer MUST reset the
 "time-at-xxx (integer)" Event Time Job Status attributes according to
 Section 5.3.14.  An implementation MAY use both implementation
 alternatives, depending on warm versus cold start, respectively.

5.4.30. printer-current-time (dateTime|unknown)

 This RECOMMENDED Printer attribute indicates the current date and
 time.  This value is used to populate the Event Time Job Status
 attributes "date-time-at-creation", "date-time-at-processing", and
 "date-time-at-completed" (see Section 5.3.14).
 This value is obtained on a "best effort" basis and in practice does
 not have to be precise in order to be useful.  A Printer
 implementation sets the value of this attribute by obtaining the date
 and time via some implementation-dependent means, such as getting the
 value from a network time server, initialization at time of
 manufacture, or setting by an Administrator.  See [RFC3196] and
 [PWG5100.19] for examples.  If an implementation supports this
 attribute and the implementation knows that it has not yet been set,
 then the implementation MUST return the value of this attribute using
 the out-of-band 'unknown', meaning the value is not yet known.  See
 the beginning of Section 5.1.
 The time zone of this attribute might not be the time zone used by
 people located near the Printer or device.  The Client MUST NOT
 expect the time zone of any received 'dateTime' value to be in the
 time zone of the Client or in the time zone of the people located
 near the Printer.

Sweet & McDonald Standards Track [Page 163] RFC 8011 IPP/1.1: Model and Semantics January 2017

 The Client SHOULD display any dateTime attributes to the user in the
 Client's local time by converting the 'dateTime' value returned by
 the server to the time zone of the Client, rather than using the time
 zone returned by the Printer in attributes that use the 'dateTime'
 attribute syntax.
 Note: Prior versions of this document incorrectly specified the use
 of the 'no-value' out-of-band value when the current date and time
 had not been set.  The correct out-of-band value is 'unknown', since
 there is always an intrinsic current date and time.

5.4.31. multiple-operation-time-out (integer(1:MAX))

 This RECOMMENDED Printer attribute identifies the minimum time (in
 seconds) that the Printer waits for additional Send-Document or
 Send-URI operations to follow a still-open Job before taking any
 recovery actions, such as the ones indicated in Section 4.3.1.  If
 the Printer supports the Create-Job and Send-Document operations (see
 Sections 4.2.4 and 4.3.1), it MUST support this attribute.
 Printers SHOULD use a value between '60' and '240' (seconds).  An
 implementation MAY allow an Administrator to set this attribute by
 means not defined in this document.  If so, the Administrator MAY be
 able to set values outside this range.

5.4.32. compression-supported (1setOf type2 keyword)

 This REQUIRED Printer attribute identifies the set of supported
 compression algorithms for Document data.  Compression only applies
 to the Document data; compression does not apply to the encoding of
 the IPP operation itself.  The supported values are used to validate
 the Client-supplied "compression" operation attributes in Print-Job
 and Send-Document requests.
 Standard 'keyword' values defined in this document are:
 o  'none': no compression is used.
 o  'deflate': ZIP inflate/deflate compression technology described in
    RFC 1951 [RFC1951].
 o  'gzip': GNU zip compression technology described in RFC 1952
    [RFC1952].
 o  'compress': UNIX compression technology described in RFC 1977
    [RFC1977].

Sweet & McDonald Standards Track [Page 164] RFC 8011 IPP/1.1: Model and Semantics January 2017

5.4.33. job-k-octets-supported (rangeOfInteger(0:MAX))

 This Printer attribute specifies the upper and lower bounds of total
 sizes of Jobs in K octets, i.e., in units of 1024 octets.  The
 supported values are used to validate the Client-supplied
 "job-k-octets" operation attribute in Job Creation requests.  The
 corresponding Job Description attribute "job-k-octets" is defined in
 Section 5.3.17.1.

5.4.34. job-impressions-supported (rangeOfInteger(0:MAX))

 This RECOMMENDED Printer attribute specifies the upper and lower
 bounds for the number of Impressions per Job.  The supported values
 are used to validate the Client-supplied "job-impressions" operation
 attribute in Job Creation requests.  The corresponding Job
 Description attribute "job-impressions" is defined in
 Section 5.3.17.2.

5.4.35. job-media-sheets-supported (rangeOfInteger(1:MAX))

 This Printer attribute specifies the upper and lower bounds for the
 number of Media Sheets per Job.  The supported values are used to
 validate the Client-supplied "job-media-sheets" operation attribute
 in Job Creation requests.  The corresponding Job attribute
 "job-media-sheets" is defined in Section 5.3.17.3.

5.4.36. pages-per-minute (integer(0:MAX))

 This RECOMMENDED Printer attribute specifies the nominal number of
 pages per minute to the nearest whole number that can be generated by
 this Printer (e.g., simplex, black-and-white).  This attribute is
 informative, not a service guarantee.  Generally, it is the value
 used in the marketing literature to describe the speed of the device.
 A value of 0 indicates a device that takes more than two minutes to
 process a page.

5.4.37. pages-per-minute-color (integer(0:MAX))

 This RECOMMENDED Printer attribute specifies the nominal number of
 pages per minute to the nearest whole number that can be generated by
 this Printer when printing color (e.g., simplex, color).  For
 purposes of this attribute, the meaning of "color" is the same as
 that for the "color-supported" attribute; namely, the device is
 capable of any type of color printing at all, including highlight
 color.  This attribute is informative, not a service guarantee.
 Generally, it is the value used in the marketing literature to
 describe the color capabilities of this device.

Sweet & McDonald Standards Track [Page 165] RFC 8011 IPP/1.1: Model and Semantics January 2017

 A value of 0 indicates a device that takes more than two minutes to
 process a page in color.
 If a color device has several color modes, it MAY use the
 "pages-per-minute" value for this attribute that corresponds to the
 mode that produces the highest number.
 Printers that are black-and-white only MUST NOT support this
 attribute.  If this attribute is present, then the "color-supported"
 Printer Description attribute MUST be present and have a 'true'
 value.
 The values of the "pages-per-minute" and "pages-per-minute-color"
 attributes returned by the Get-Printer-Attributes operation MAY be
 affected by the "document-format" attribute supplied by the Client in
 the Get-Printer-Attributes request.  In other words, the
 implementation MAY have different speeds, depending on the Document
 format being processed.  See Section 4.2.5.1 ("Get-Printer-Attributes
 Request").

6. Conformance

 This section describes conformance issues and requirements.  This
 document introduces model entities such as objects, operations,
 attributes, attribute syntaxes, and attribute values.  The following
 sections describe the conformance requirements that apply to these
 model entities.

6.1. Client Conformance Requirements

 This section describes the conformance requirements for a Client (see
 Section 3.1), whether it be:
 1.  contained within software controlled by an End User, e.g.,
     activated by the "Print" menu item in an application that sends
     IPP requests, or
 2.  the print server component that sends IPP requests to either an
     Output Device or another "downstream" print server.
 A conforming Client supports all REQUIRED operations as defined in
 this document.  For each attribute included in an operation request,
 a conforming Client MUST supply a value whose type and value syntax
 conforms to the requirements specified in Sections 4 and 5 of this
 document.  A conforming Client MAY supply any Standards Track
 extensions and/or vendor extensions in an operation request, as long
 as the extensions meet the requirements in Section 7.

Sweet & McDonald Standards Track [Page 166] RFC 8011 IPP/1.1: Model and Semantics January 2017

 While this document does not define conformance requirements for the
 user interfaces provided by IPP Clients or their applications, best
 practices for user interfaces are defined in [PWG5100.19].
 A Client MUST be able to accept any of the attribute syntaxes defined
 in Section 5.1, including their full range, that can be returned to
 it in a response from a Printer.  In particular, for each attribute
 that the Client supports whose attribute syntax is 'text', the Client
 MUST accept and process both the 'textWithoutLanguage' and
 'textWithLanguage' forms.  Similarly, for each attribute that the
 Client supports whose attribute syntax is 'name', the Client MUST
 accept and process both the 'nameWithoutLanguage' and
 'nameWithLanguage' forms.  For presentation purposes, truncation of
 long attribute values is not recommended.  A recommended approach
 would be for the Client implementation to allow the user to scroll
 through long attribute values.
 A response MAY contain attribute groups, attributes, attribute
 syntaxes, values, and status-code values that the Client does not
 expect.  Therefore, a Client implementation MUST gracefully handle
 such responses and not refuse to interoperate with a conforming
 Printer that is returning Standards Track extensions or vendor
 extensions, including attribute groups, attributes, attribute
 syntaxes, attribute values, status-code values, and out-of-band
 attribute values that conform to Section 7.  Clients can choose to
 ignore any parameters, attribute groups, attributes, attribute
 syntaxes, or values that they do not understand.
 While a Client is sending data to a Printer, it SHOULD do its best to
 prevent a channel from being closed by a lower layer when the channel
 is blocked (i.e., flow-controlled off) for whatever reason, e.g.,
 'out of paper' or 'Job ahead hasn't freed up enough memory'.
 However, the layer that launched the print submission (e.g., an
 End User) MAY close the channel in order to cancel the Job.  When a
 Client closes a channel, a Printer MAY print all or part of the
 received portion of the Document.  See the Encoding and Transport
 document [RFC8010] for more details.
 A Client MUST support Client Authentication as defined in [RFC8010].
 A Client SHOULD support Operation Privacy and Server Authentication
 as defined in [RFC8010].  See also Section 9 of this document.

Sweet & McDonald Standards Track [Page 167] RFC 8011 IPP/1.1: Model and Semantics January 2017

6.2. IPP Object Conformance Requirements

 This section specifies the conformance requirements for conforming
 implementations of IPP objects (see Section 3).  These requirements
 apply to an IPP object whether it is:
 1)  an (embedded) device component that accepts IPP requests and
     controls the device, or
 2)  a component of a print server that accepts IPP requests (where
     the print server controls one or more networked devices using IPP
     or other protocols).

6.2.1. Objects

 Conforming implementations MUST implement all of the model objects as
 defined in this document in the indicated sections:
 Section 3.1 - Printer Object
 Section 3.2 - Job Object

6.2.2. Operations

 Conforming IPP object implementations MUST implement all of the
 REQUIRED model operations, including REQUIRED responses, as defined
 in this document in the indicated sections.  Table 20 lists the
 operations for a Printer, while Table 21 lists the operations for
 a Job.

Sweet & McDonald Standards Track [Page 168] RFC 8011 IPP/1.1: Model and Semantics January 2017

       +----------------------------------------+-------------+
       | Operation                              | Conformance |
       +----------------------------------------+-------------+
       | Print-Job (Section 4.2.1)              | REQUIRED    |
       +----------------------------------------+-------------+
       | Print-URI (Section 4.2.2)              | OPTIONAL    |
       +----------------------------------------+-------------+
       | Validate-Job (Section 4.2.3)           | REQUIRED    |
       +----------------------------------------+-------------+
       | Create-Job (Section 4.2.4)             | RECOMMENDED |
       +----------------------------------------+-------------+
       | Get-Printer-Attributes (Section 4.2.5) | REQUIRED    |
       +----------------------------------------+-------------+
       | Get-Jobs (Section 4.2.6)               | REQUIRED    |
       +----------------------------------------+-------------+
       | Pause-Printer (Section 4.2.7)          | OPTIONAL    |
       +----------------------------------------+-------------+
       | Resume-Printer (Section 4.2.8)         | OPTIONAL    |
       +----------------------------------------+-------------+
       | Purge-Jobs (Section 4.2.9)             | SHOULD NOT  |
       +----------------------------------------+-------------+
       Table 20: Conformance Requirements for Printer Operations
         +------------------------------------+-------------+
         | Operation                          | Conformance |
         +------------------------------------+-------------+
         | Send-Document (Section 4.3.1)      | RECOMMENDED |
         +------------------------------------+-------------+
         | Send-URI (Section 4.3.2)           | RECOMMENDED |
         +------------------------------------+-------------+
         | Cancel-Job (Section 4.3.3)         | REQUIRED    |
         +------------------------------------+-------------+
         | Get-Job-Attributes (Section 4.3.4) | REQUIRED    |
         +------------------------------------+-------------+
         | Hold-Job (Section 4.3.5)           | OPTIONAL    |
         +------------------------------------+-------------+
         | Release-Job (Section 4.3.6)        | OPTIONAL    |
         +------------------------------------+-------------+
         | Restart-Job (Section 4.3.7)        | SHOULD NOT  |
         +------------------------------------+-------------+
         Table 21: Conformance Requirements for Job Operations

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 Conforming IPP objects MUST support all REQUIRED operation attributes
 and all values of such attributes if so indicated in the description.
 Conforming IPP objects MUST ignore all unsupported or unknown
 operation attributes or Operation Attributes groups received in a
 request but MUST reject a request that contains a supported operation
 attribute that contains an unsupported value.
 Conforming IPP objects MAY return operation responses that contain
 attribute groups, attribute names, attribute syntaxes, attribute
 values, and status-code values that are extensions to this
 specification.  The additional attribute groups MAY occur in any
 order.
 The following section on object attributes specifies the support
 required for object attributes.

6.2.3. IPP Object Attributes

 Conforming IPP objects MUST support all of the REQUIRED object
 attributes, as defined in this document in the indicated sections.
 If an object supports an attribute, it MUST support only those values
 specified in this document or through the extension mechanism
 described in Section 6.2.5.  It MAY support any non-empty subset of
 these values.  That is, it MUST support at least one of the specified
 values and at most all of them.

6.2.4. Versions

 IPP/1.1 Clients MUST meet the conformance requirements for Clients
 specified in this document and [RFC8010].  IPP/1.1 Clients MUST be
 capable of sending requests containing a "version-number" parameter
 with a value of '1.1'.
 IPP/1.1 Printer and Job objects MUST meet the conformance
 requirements for IPP objects specified in this document and
 [RFC8010].  IPP/1.1 objects MUST accept requests containing a
 "version-number" parameter with a '1.1' value or reject the request
 if the operation is not supported.

Sweet & McDonald Standards Track [Page 170] RFC 8011 IPP/1.1: Model and Semantics January 2017

 It is beyond the scope of this specification to mandate conformance
 with other IPP versions.  However, IPP was deliberately designed to
 make supporting different versions easy.  IPP/1.1 Printer
 implementations MUST:
 o  decode and process any well-formed IPP/1.1 request, and
 o  respond appropriately with a response containing the same
    "version-number" parameter value used by the Client in the
    request.
 IPP/1.1 Client implementations MUST:
 o  decode and process any well-formed IPP/1.1 response.
 IPP Clients SHOULD try supplying alternate version numbers if they
 receive a 'server-error-version-not-supported' error in a response.

6.2.5. Extensions

 A conforming IPP object MAY support Standards Track extensions and
 vendor extensions, as long as the extensions meet the requirements
 specified in Section 7.
 For each attribute included in an operation response, a conforming
 IPP object MUST return a value whose type and value syntax conforms
 to the requirements specified in Sections 4 and 5 of this document.

6.2.6. Attribute Syntaxes

 An IPP object MUST be able to accept any of the attribute syntaxes
 defined in Section 5.1, including their full range, in any operation
 in which a Client can supply attributes or the Administrator can
 configure attributes (by means outside the scope of this IPP/1.1
 document).  In particular, for each attribute that the IPP object
 supports whose attribute syntax is 'text', the IPP object MUST accept
 and process both the 'textWithoutLanguage' and 'textWithLanguage'
 forms.  Similarly, for each attribute that the IPP object supports
 whose attribute syntax is 'name', the IPP object MUST accept and
 process both the 'nameWithoutLanguage' and 'nameWithLanguage' forms.
 Furthermore, an IPP object MUST return attributes to the Client in
 operation responses that conform to the syntaxes specified in
 Section 5.1, including their full range if supplied previously by a
 Client.

Sweet & McDonald Standards Track [Page 171] RFC 8011 IPP/1.1: Model and Semantics January 2017

6.2.7. Security

 An IPP Printer implementation SHOULD contain support for Client
 Authentication as defined in the IPP/1.1 Encoding and Transport
 document [RFC8010].  A Printer implementation MAY allow an
 Administrator to configure the Printer so that all, some, or none of
 the users are authenticated.  See also Section 9 of this document.
 An IPP Printer implementation SHOULD contain support for Operation
 Privacy and Server Authentication as defined in [RFC8010].  A Printer
 implementation MAY allow an Administrator to configure the degree of
 support for Operation Privacy and Server Authentication.  See also
 Section 9 of this document.
 Security MUST NOT be compromised when a Client supplies a lower
 "version-number" parameter in a request.  For example, if a Printer
 conforming to IPP/1.1 accepts version '1.0' requests and is
 configured to enforce Digest Authentication, it MUST do the same for
 a version '1.0' request.

6.3. Charset and Natural Language Requirements

 All Clients and IPP objects MUST support the 'utf-8' charset as
 defined in Section 5.1.8.
 IPP objects MUST be able to accept any Client request that correctly
 uses the "attributes-natural-language" operation attribute or the
 Natural Language Override mechanism on any individual attribute
 whether or not the natural language is supported by the IPP object.
 If an IPP object supports a natural language, then it MUST be able to
 translate (perhaps by table lookup) all generated 'text' or 'name'
 attribute values into one of the supported languages (see
 Section 4.1.4).

Sweet & McDonald Standards Track [Page 172] RFC 8011 IPP/1.1: Model and Semantics January 2017

7. IANA Considerations

 This section describes the procedures for defining Standards Track
 and vendor extensions to this document.  This affects the following
 subregistries of the IANA IPP registry:
 1.  Objects
 2.  Attributes
 3.  Keyword Attribute Values
 4.  Enum Attribute Values
 5.  Attribute Group Tags
 6.  Out-of-Band Attribute Value Tags
 7.  Attribute Syntaxes
 8.  Operations
 9.  Status-Code Values
 Extensions registered for use with IPP are OPTIONAL for Client and
 IPP object conformance to the IPP/1.1 Model and Semantics document
 (this document).
 These extension procedures are aligned with the guidelines as set
 forth in "Guidelines for Writing an IANA Considerations Section in
 RFCs" [RFC5226].  Appendix A describes how to propose new
 registrations for consideration.  IANA will reject registration
 proposals that leave out required information or do not follow the
 appropriate format described in Appendix A.  The IPP/1.1 Model and
 Semantics document can also be extended by an appropriate
 Standards Track document that specifies any of the above extensions.
 The IANA policy (using terms defined in [RFC5226]) for all extensions
 is Specification Required, Expert Review, or First Come First Served
 as documented in the following subsections.  Registrations submitted
 to IANA are forwarded to the IPP Designated Expert(s) who reviews the
 proposal on a mailing list that the Designated Expert(s) keeps for
 this purpose.  Initially, that list is the mailing list used by the
 PWG IPP WG:
    ipp@pwg.org

Sweet & McDonald Standards Track [Page 173] RFC 8011 IPP/1.1: Model and Semantics January 2017

 The IPP Designated Expert(s) is appointed by the IESG Area Director
 responsible for IPP, according to [RFC5226].
 In addition, the IANA-PRINTER-MIB [RFC3805] has been updated to
 reference this document; the current version is available from
 <http://www.iana.org>.

7.1. Object Extensions

 The IANA policy (using terms defined in [RFC5226]) for object
 extensions was formerly Expert Review; this document changes the
 policy to Specification Required.

7.2. Attribute Extensibility

 Since attribute names are type2 keywords (see Section 5.1.4), the
 IANA policy (using terms defined in [RFC5226]) for attribute
 extensions is Expert Review.
 For vendor attribute extensions, implementors SHOULD use keywords
 with a suitable distinguishing prefix such as 'smiNNN-' where NNN is
 an SMI Private Enterprise Number (PEN) [IANA-PEN].  For example, if
 the company Example Corp. had obtained the SMI PEN 32473, then a
 vendor attribute 'foo' would be 'smi32473-foo'.
    Note: Prior versions of this document recommended using a fully
    qualified domain name [RFC1035] as the prefix (e.g.,
    'example.com-foo'), and many IPP implementations have also used
    reversed domain names (e.g., 'com.example-foo').  Domain names
    have proven problematic due to the length of some domain names,
    parallel use of country-specific domain names (e.g.,
    'example.co.jp-foo'), and changes in ownership of domain names.
 If a new Printer attribute is defined and its values can be affected
 by a specific Document format, its specification needs to contain the
 following sentence:
    "The value of this attribute returned in a Get-Printer-Attributes
    response MAY depend on the "document-format" attribute supplied
    (see Section 4.2.5.1) of the IPP/1.1 Model and Semantics
    document."
 If the specification does not, then its value in the
 Get-Printer-Attributes response MUST NOT depend on the
 "document-format" attribute supplied in the request.

Sweet & McDonald Standards Track [Page 174] RFC 8011 IPP/1.1: Model and Semantics January 2017

 When a new Job Template attribute is registered, the value of the
 Printer attributes MAY vary with "document-format" supplied in the
 request without the specification having to indicate so.

7.3. Keyword Extensibility

 The IANA policy (using terms defined in [RFC5226]) for type1 keyword
 extensions is Specification Required.  The IANA policy for type2
 keyword extensions is Expert Review.  The IANA policy for vendor
 keyword extensions is First Come First Served.  Only attributes using
 the type1 and type2 keyword syntax can be registered in the IANA IPP
 registry.
    Note: The type1 or type2 prefix on the basic attribute syntax is
    provided only to communicate the IANA policy required for
    registration and is not represented in IPP messages.  Both type1
    and type2 'keyword' values are represented using the same
    'keyword' value tag.
 For type1 and type2 keywords, the proposer includes the name of the
 keyword in the registration proposal, and the name is part of the
 technical review.
 For vendor keyword extensions, implementors SHOULD either:
 a.  follow attribute-specific guidance such as the guidance defined
     in [PWG5101.1], or
 b.  use keywords with a suitable distinguishing prefix, such as
     'smiNNN-' where NNN is an SMI Private Enterprise Number (PEN)
     [IANA-PEN].
 For example, if the company Example Corp. had obtained the
 SMI PEN 32473, then a vendor keyword 'foo' would be 'smi32473-foo'.
    Note: Prior versions of this document recommended using a fully
    qualified domain name [RFC1035] as the prefix (e.g.,
    'example.com-foo'), and many IPP implementations have also used
    reversed domain names (e.g., 'com.example-foo').  Domain names
    have proven problematic due to the length of some domain names,
    parallel use of country-specific domain names (e.g.,
    'example.co.jp-foo'), and changes in ownership of domain names.
 When a type2 keyword extension is approved, the IPP Designated
 Expert(s) becomes the point of contact for any future maintenance
 that might be required for that registration.

Sweet & McDonald Standards Track [Page 175] RFC 8011 IPP/1.1: Model and Semantics January 2017

7.4. Enum Extensibility

 The IANA policy (using terms defined in [RFC5226]) for type1 enum
 extensions is Specification Required.  The IANA policy for type2 enum
 extensions is Expert Review.  The IANA policy for vendor enum
 extensions is First Come First Served.  Only attributes using the
 type1 and type2 enum syntax can be registered in the IANA IPP
 registry.
    Note: The type1 or type2 prefix on the basic attribute syntax is
    provided only to communicate the IANA policy required for
    registration and is not represented in IPP messages.  Both type1
    and type2 enum values are represented using the same enum
    value tag.
 For vendor enum extensions, implementors MUST use values in the
 reserved integer range, which is 0x40000000 to 0x7fffffff.
 Implementors SHOULD consult with the IPP Designated Expert(s) to
 reserve vendor extension value(s) for their usage.
 When a type1 or type2 enum extension is approved, the IPP Designated
 Expert(s), in consultation with IANA, assigns the next available enum
 number for each enum value.
 When a type2 enum extension is approved, the IPP Designated Expert(s)
 becomes the point of contact for any future maintenance that might be
 required for that registration.

7.5. Attribute Group Extensibility

 The IANA policy (using terms defined in [RFC5226]) for attribute
 group extensions was formerly Expert Review; this document changes
 the policy to Specification Required.
 For attribute groups, the IPP Designated Expert(s), in consultation
 with IANA, assigns the next attribute group tag code in the
 appropriate range as specified in [RFC8010].

7.6. Out-of-Band Attribute Value Extensibility

 The IANA policy (using terms defined in [RFC5226]) for out-of-band
 attribute value extensions was formerly Expert Review; this document
 changes the policy to Specification Required.
 For out-of-band attribute value tags, the IPP Designated Expert(s),
 in consultation with IANA, assigns the next out-of-band attribute
 value tag code in the appropriate range as specified in [RFC8010].

Sweet & McDonald Standards Track [Page 176] RFC 8011 IPP/1.1: Model and Semantics January 2017

7.7. Attribute Syntax Extensibility

 The IANA policy (using terms defined in [RFC5226]) for attribute
 syntax extensions was formerly Expert Review; this document changes
 the policy to Specification Required.  The IANA policy for vendor
 attribute syntax extensions (tags 0x40000000 to 0x7fffffff) is First
 Come First Served.  Only attribute syntaxes in the range of
 0x00000000 to 0x3fffffff can be registered in the IANA IPP registry.
 For vendor attribute syntax extensions, implementors MUST use values
 in the reserved integer range, which is 0x40000000 to 0x7fffffff.
 Implementors SHOULD consult with the IPP Designated Expert(s) to
 reserve vendor extension value(s) for their usage.
 For registered attribute syntaxes, the IPP Designated Expert(s), in
 consultation with IANA, assigns the next attribute syntax tag in the
 appropriate range as specified in [RFC8010].

7.8. Operation Extensibility

 The IANA policy (using terms defined in [RFC5226]) for operation
 extensions is Expert Review.  The IANA policy for vendor operation
 extensions (values 0x4000 to 0x7fff) is First Come First Served.
 Only operation codes in the range of 0x0000 to 0x3fff can be
 registered in the IANA IPP registry.
 For vendor operation extensions, implementors MUST use values in the
 reserved integer range, which is 0x4000 to 0x7fff.  Implementors
 SHOULD consult with the IPP Designated Expert(s) to reserve vendor
 extension value(s) for their usage.
 For registered operation extensions, the IPP Designated Expert(s), in
 consultation with IANA, assigns the next "operation-id" code as
 specified in Section 5.4.15.

Sweet & McDonald Standards Track [Page 177] RFC 8011 IPP/1.1: Model and Semantics January 2017

7.9. Status-Code Extensibility

 The IANA policy (using terms defined in [RFC5226]) for status-code
 extensions is Expert Review.  The IANA policy for vendor status-code
 extensions (codes 0x0n80 to 0x0nff, for n = 0 to 5) is First Come
 First Served.  Only status-code values in the range of 0x0n00 to
 0x0n7f can be registered in the IANA IPP registry.
 The status-code values are allocated in ranges as specified in
 Appendix B for each status-code class:
 "informational" - Request received, continuing process
 "successful" - The action was successfully received, understood, and
 accepted
 "redirection" - Further action is taken in order to complete the
 request
 "client-error" - The request contains bad syntax or cannot be
 fulfilled
 "server-error" - The IPP object failed to fulfill an apparently valid
 request
 For vendor operation status-code extensions, implementors MUST use
 the top of each range (0x0n80 to 0x0nff) as specified in Appendix B.
 Implementors SHOULD consult with the IPP Designated Expert(s) to
 reserve vendor extension value(s) for their usage.
 For registered operation status-code values, the IPP Designated
 Expert(s), in consultation with IANA, assigns the next status-code in
 the appropriate class range as specified in Appendix B.

Sweet & McDonald Standards Track [Page 178] RFC 8011 IPP/1.1: Model and Semantics January 2017

8. Internationalization Considerations

 Some of the attributes have values that are text strings and names
 that are intended for human understanding rather than machine
 understanding (see the 'text' and 'name' attribute syntaxes in
 Sections 5.1.2 and 5.1.3).
 In each operation request, the Client
 o  identifies the charset and natural language of the request that
    affects each supplied 'text' and 'name' attribute value, and
 o  requests the charset and natural language for attributes returned
    by the IPP object in operation responses (as described in
    Section 4.1.4.1).
 In addition, the Client MAY separately and individually identify the
 Natural Language Override of a supplied 'text' or 'name' attribute
 using the 'textWithLanguage' and 'nameWithLanguage' techniques
 described in Sections 5.1.2.2 and 5.1.3.2, respectively.
 All IPP objects MUST support the UTF-8 [RFC3629] charset in all
 'text' and 'name' attributes supported.  If an IPP object supports
 more than the UTF-8 charset, the object MUST convert between them in
 order to return the requested charset to the Client according to
 Section 4.1.4.2.  If an IPP object supports more than one natural
 language, the object SHOULD return 'text' and 'name' values in the
 natural language requested where those values are generated by the
 Printer (see Section 4.1.4.1).
 For Printers that support multiple charsets and/or multiple natural
 languages in 'text' and 'name' attributes, different Jobs might have
 been submitted in differing charsets and/or natural languages.  All
 responses MUST be returned in the charset requested by the Client.
 However, the Get-Jobs operation uses the 'textWithLanguage' and
 'nameWithLanguage' mechanisms to identify the differing natural
 languages with each Job attribute returned.
 The Printer also has configured charset and natural language
 attributes.  The Client can query the Printer to determine the list
 of charsets and natural languages supported by the Printer and what
 the Printer's configured values are.  See the "charset-configured",
 "charset-supported", "natural-language-configured", and
 "generated-natural-language-supported" Printer Description attributes
 for more details.

Sweet & McDonald Standards Track [Page 179] RFC 8011 IPP/1.1: Model and Semantics January 2017

 The "charset-supported" attribute identifies the supported charsets.
 If a charset is supported, the IPP object MUST be capable of
 converting to and from that charset into any other supported charset.
 In many cases, an IPP object will support only one charset, and it
 MUST be the UTF-8 charset.
 The "charset-configured" attribute identifies the one supported
 charset that is the native charset, given the current configuration
 of the IPP object (Administrator defined).
 The "generated-natural-language-supported" attribute identifies the
 set of supported natural languages for generated messages; it is not
 related to the set of natural languages that MUST be accepted for
 Client-supplied 'text' and 'name' attributes.  For Client-supplied
 'text' and 'name' attributes, an IPP object MUST accept ALL supplied
 natural languages.  For example, if a Client supplies a Job name that
 is in 'fr-ca' but the Printer only generates 'en-us', the Printer
 object MUST still accept the Job name value.
 The "natural-language-configured" attribute identifies the one
 supported natural language for generated messages that is the native
 natural language, given the current configuration of the IPP object
 (Administrator defined).
 Attributes of types 'text' and 'name' are populated from different
 sources.  These attributes can be categorized into the following
 groups (depending on the source of the attribute):
 1.  Some attributes are supplied by the Client (e.g., the
     Client-supplied "job-name", "document-name", and
     "requesting-user-name" operation attributes along with the
     corresponding Job's "job-name" and "job-originating-user-name"
     attributes).  The IPP object MUST accept these attributes in any
     natural language no matter what the set of supported languages
     for generated messages.
 2.  Some attributes are supplied by the Administrator (e.g., the
     Printer's "printer-name" and "printer-location" attributes).
     These can also be in any natural language.  If the natural
     language for these attributes is different than what a Client
     requests, then they MUST be reported using the Natural Language
     Override mechanism.

Sweet & McDonald Standards Track [Page 180] RFC 8011 IPP/1.1: Model and Semantics January 2017

 3.  Some attributes are supplied by the device manufacturer (e.g.,
     the Printer's "printer-make-and-model" attribute).  These can
     also be in any natural language.  If the natural language for
     these attributes is different than what a Client requests, then
     they MUST be reported using the Natural Language Override
     mechanism.
 4.  Some attributes are supplied by the Operator (e.g., the Job's
     "job-message-from-operator" attribute).  These can also be in any
     natural language.  If the natural language for these attributes
     is different than what a Client requests, then they MUST be
     reported using the Natural Language Override mechanism.
 5.  Some attributes are generated by the IPP object (e.g., the Job's
     "job-state-message" attribute, the Printer's
     "printer-state-message" attribute, and the "status-message"
     operation attribute).  These attributes can only be in one of the
     "generated-natural-language-supported" natural languages.  If a
     Client requests some natural language for these attributes other
     than one of the supported values, the IPP object SHOULD respond
     using the value of the "natural-language-configured" attribute
     (using the Natural Language Override mechanism if needed).
 The 'text' and 'name' attributes specified in this version of this
 document (additional ones will be registered according to the
 procedures in Section 7) are shown in Table 22.
 +-----------------------------------+-------------------------------+
 | Attributes                        | Source                        |
 +-----------------------------------+-------------------------------+
 | Operation Attributes:             |                               |
 |                                   |                               |
 | job-name (name)                   | Client                        |
 | document-name (name)              | Client                        |
 | requesting-user-name (name)       | Client                        |
 | status-message (text)             | Job or Printer                |
 | detailed-status-message (text)    | Job or Printer (note 1)       |
 | document-access-error (text)      | Job or Printer (note 1)       |
 |                                   |                               |
 | Job Template Attributes:          |                               |
 |                                   |                               |
 | job-hold-until (keyword | name)   | Client matches Administrator- |
 |                                   | configured                    |
 | job-hold-until-default (keyword | | Client matches Administrator- |
 | name)                             | configured                    |
 | job-hold-until-supported (keyword | Client matches Administrator- |
 | | name)                           | configured                    |

Sweet & McDonald Standards Track [Page 181] RFC 8011 IPP/1.1: Model and Semantics January 2017

 | job-sheets (keyword | name)       | Client matches Administrator- |
 |                                   | configured                    |
 | job-sheets-default (keyword |     | Client matches Administrator- |
 | name)                             | configured                    |
 | job-sheets-supported (keyword |   | Client matches Administrator- |
 | name)                             | configured                    |
 | media (keyword | name)            | Client matches Administrator- |
 |                                   | configured                    |
 | media-default (keyword | name)    | Client matches Administrator- |
 |                                   | configured                    |
 | media-supported (keyword | name)  | Client matches Administrator- |
 |                                   | configured                    |
 | media-ready (keyword | name)      | Client matches Administrator- |
 |                                   | configured                    |
 |                                   |                               |
 | Job Description Attributes:       |                               |
 |                                   |                               |
 | job-name (name)                   | Client or Printer             |
 | job-originating-user-name (name)  | Printer                       |
 | job-state-message (text)          | Job or Printer                |
 | output-device-assigned            | Administrator                 |
 | (name(127))                       |                               |
 | job-message-from-operator         | Operator                      |
 | (text(127))                       |                               |
 | job-detailed-status-messages      | Job or Printer (note 1)       |
 | (1setOf text)                     |                               |
 | job-document-access-errors        | Job or Printer (note 1)       |
 | (1setOf text)                     |                               |
 |                                   |                               |
 | Printer Description Attributes:   |                               |
 |                                   |                               |
 | printer-name (name(127))          | Administrator                 |
 | printer-location (text(127))      | Administrator                 |
 | printer-info (text(127))          | Administrator                 |
 | printer-make-and-model            | Administrator or manufacturer |
 | (text(127))                       |                               |
 | printer-state-message (text)      | Printer                       |
 | printer-message-from-operator     | Operator                      |
 | (text(127))                       |                               |
 +-----------------------------------+-------------------------------+
                Table 22: 'text' and 'name' Attributes
 Note 1: Neither the Printer nor the Client localizes these message
 attributes, since they are intended for use by the Administrator or
 other experienced technical persons.

Sweet & McDonald Standards Track [Page 182] RFC 8011 IPP/1.1: Model and Semantics January 2017

9. Security Considerations

 It is difficult to anticipate the security risks that might exist in
 any given IPP environment.  For example, if IPP is used within a
 given small business over a private LAN with physical security, the
 risks of exposing Document data can be low enough that the business
 will choose not to use encryption on that data.  However, if the
 connection between the Client and the IPP object is over a public
 network, the Client can protect the content of the information during
 transmission through the network with encryption.
 Furthermore, the value of the information being printed can vary from
 one IPP environment to the next.  Printing payroll checks, for
 example, would have a different value than printing public
 information from a file.  There is also the possibility of denial-of-
 service attacks, but denial-of-service attacks against printing
 resources are not well understood, and there are no published
 precedents regarding this scenario.
 Once the authenticated identity of the requester has been supplied to
 the IPP object, the object uses that identity to enforce any
 authorization policy that might be in place.  For example, one site's
 policy might be that only the Job owner is allowed to cancel a Job.
 The details and mechanisms to set up a particular access control
 policy are not part of this document and are typically established
 via some other type of administrative or access control framework.
 However, there are operation status-code values that allow an IPP
 server to return information back to a Client about any potential
 access control violations for an IPP object.
 During a Job Creation request, the Client's identity is recorded in
 the Job object in an implementation-defined attribute.  This
 information can be used to verify a Client's identity for subsequent
 operations on that Job object in order to enforce any access control
 policy that might be in effect.  See Section 9.3 below for more
 details.  This and other information stored in the Job object can
 also be considered personal or sensitive in nature and can be
 filtered out as part of a configured privacy policy (Section 9.4).
 Since the security levels or the specific threats that an
 Administrator can be concerned with cannot be anticipated, IPP
 implementations MUST be capable of operating with different security
 mechanisms and security policies as required by the individual
 installation.  Security policies might vary from very strong to very
 weak, or to none at all, and corresponding security mechanisms will
 be required.

Sweet & McDonald Standards Track [Page 183] RFC 8011 IPP/1.1: Model and Semantics January 2017

9.1. Security Scenarios

 The following sections describe specific security attacks for IPP
 environments.  Where examples are provided, they are illustrative of
 the environment and not an exhaustive set.

9.1.1. Client and Server in the Same Security Domain

 This environment is typical of internal networks where traditional
 office workers print the output of personal productivity applications
 on shared workgroup Printers, or where batch applications print their
 output on large production Printers.  Although the identity of the
 user has been authenticated and can be trusted in this environment, a
 user might want to protect the content of a Document against such
 attacks as eavesdropping, replaying, or tampering by using a secure
 transport such as TLS [RFC5246].

9.1.2. Client and Server in Different Security Domains

 Examples of this environment include printing a Document created by
 the Client on a publicly available Printer, such as at a commercial
 print shop, or printing a Document remotely on a business associate's
 Printer.  This latter operation is functionally equivalent to sending
 the Document to the business associate as a facsimile.  Printing
 sensitive information on a Printer in a different security domain
 requires strong security measures.  In this environment,
 authentication of the Printer is required as well as protection
 against unauthorized use of print resources.  Since the Document
 crosses security domains, protection against eavesdropping and
 Document tampering is also required.  It will also be important in
 this environment to protect Printers against "spamming" and malicious
 Document content -- authentication and Document data pre-scanning can
 be used to minimize those threats.

9.1.3. Print by Reference

 When the Document is not stored on the Client, printing can be done
 by reference.  That is, the print request can contain a reference, or
 pointer, to the Document instead of the actual Document itself -- see
 Sections 4.2.2 and 4.3.2.  Standard methods currently do not exist
 for remote entities to "assume" the credentials of a Client for
 forwarding requests to a third party.  It is anticipated that print
 by reference will be used to access "public" Documents.  Note that
 sophisticated methods for authenticating "proxies" are beyond the
 scope of this IPP/1.1 document.  Because Printers typically process
 Jobs serially, print by reference is not seen as a serious denial-of-
 service threat to the referenced servers.

Sweet & McDonald Standards Track [Page 184] RFC 8011 IPP/1.1: Model and Semantics January 2017

9.2. URIs in Operation, Job, and Printer Attributes

 The "printer-uri-supported" attribute contains the Printer's URI(s).
 Its companion attribute, "uri-security-supported", identifies the
 security mechanism used for each URI listed in the
 "printer-uri-supported" attribute.  For each Printer operation
 request, a Client MUST supply only one URI in the "printer-uri"
 operation attribute.  In other words, even though the Printer
 supports more than one URI, the Client only interacts with the
 Printer using one of its URIs.  This duality is not needed for Job
 objects, since Printers will act as the "factory" for Job objects and
 a given Printer will, depending on the Printer's security
 configuration, generate the correct URI for new Job objects.

9.3. URIs for Each Authentication Mechanism

 Each URI has an authentication mechanism associated with it.  If the
 URI is the "i-th" element of "printer-uri-supported", then the
 authentication mechanism is the "i-th" element of
 "uri-authentication-supported".  For a list of possible
 authentication mechanisms, see Section 5.4.2.
 The Printer uses an authentication mechanism to determine the name of
 the user performing an operation.  This user is called the
 "authenticated user".  The credibility of authentication depends on
 the mechanism that the Printer uses to obtain the user's name.  When
 the authentication mechanism is 'none', all authenticated users are
 'anonymous'.
 During Job Creation requests, the Printer initializes the value of
 the "job-originating-user-name" attribute (see Section 5.3.6) to be
 the authenticated user.  The authenticated user in this case is
 called the "Job owner".
 If an implementation can be configured to support more than one
 authentication mechanism (see Section 5.4.2), then it MUST implement
 rules for determining equality of authenticated user names that have
 been authenticated via different authentication mechanisms.  One
 possible policy is that identical names that are authenticated via
 different mechanisms are different.  For example, a user can cancel
 his Job only if he uses the same authentication mechanism for both
 Cancel-Job and Print-Job.  Another policy is that identical names
 that are authenticated via different mechanisms are the same if the
 authentication mechanism for the later operation is not less strong
 than the authentication mechanism for the earlier Job Creation
 operation.  For example, a user can cancel his Job only if he uses
 the same or stronger authentication mechanism for Cancel-Job and
 Print-Job.  With this second policy, a Job submitted via

Sweet & McDonald Standards Track [Page 185] RFC 8011 IPP/1.1: Model and Semantics January 2017

 'requesting-user-name' authentication could be canceled via 'digest'
 authentication.  With the first policy, the Job could not be canceled
 in this way.
 A Client is able to determine the authentication mechanism used to
 create a Job.  It is the "i-th" value of the Printer's
 "uri-authentication-supported" attribute (see Section 5.4.2),
 where "i" is the index of the element of the Printer's
 "printer-uri-supported" attribute (see Section 5.4.1) equal to the
 Job's "job-printer-uri" attribute (see Section 5.3.3).

9.4. Restricted Queries

 In many IPP operations, a Client supplies a list of attributes to be
 returned in the response.  For security reasons, an IPP object can be
 configured not to return all attributes (or all values) that a Client
 requests.  The Job attributes returned MAY depend on whether the
 requesting user is the same as the user that submitted the Job.  The
 IPP object MAY even return none of the requested attributes.  In such
 cases, the status returned is the same as if the object had returned
 all requested attributes.  The Client cannot tell by such a response
 whether the requested attribute was present or absent in the object.

9.5. Operations Performed by Operators and Administrators

 For the three Printer operations Pause-Printer, Resume-Printer, and
 Purge-Jobs (see Sections 4.2.7, 4.2.8, and 4.2.9), the requesting
 user is intended to be an Operator or Administrator of the Printer
 (see Section 1).  Otherwise, the IPP Printer MUST reject the
 operation and return 'client-error-forbidden',
 'client-error-not-authenticated', or 'client-error-not-authorized'
 as appropriate.  For operations on Jobs, the requesting user is
 intended to be the Job owner or can be an Operator or Administrator
 of the Printer.  The means for authorizing an Operator or
 Administrator of the Printer are not specified in this document.

9.6. Queries on Jobs Submitted Using Non-IPP Protocols

 If the device that an IPP Printer is representing is able to accept
 Jobs using other Job submission protocols in addition to IPP, such an
 implementation SHOULD at least allow such "foreign" Jobs to be
 queried using Get-Jobs returning "job-id" and "job-uri" as 'unknown'.
 Such an implementation MAY support all of the same IPP Job attributes
 as for IPP Jobs.  The IPP object returns the 'unknown' out-of-band
 value for any requested attribute of a foreign Job that is supported
 for IPP Jobs but not for foreign Jobs.

Sweet & McDonald Standards Track [Page 186] RFC 8011 IPP/1.1: Model and Semantics January 2017

 IPP Printers SHOULD also generate "job-id" and "job-uri" values for
 such foreign Jobs, if possible, so that they can be targets of other
 IPP operations, such as Get-Job-Attributes and Cancel-Job.  Such an
 implementation also needs to deal with the problem of authentication
 of such foreign Jobs.  One approach would be to treat all such
 foreign Jobs as belonging to users other than the user of the IPP
 Client.  Another approach would be for the foreign Job to belong to
 'anonymous' -- then only authenticated Operators or Administrators of
 the IPP Printer could query the foreign Jobs with an IPP request.
 Alternatively, if the security policy is to allow users to query
 other users' Jobs, then the foreign Jobs would also be visible to an
 End User IPP Client using Get-Jobs and Get-Job-Attributes.

10. Changes since RFC 2911

 The following changes have been made since RFC 2911:
 o  Errata ID 364: Fixed range of "redirection" status-code values (to
    0x03xx).
 o  Errata ID 694: Fixed range of vendor status-code values (0x0n80 to
    0x0nff).
 o  Errata ID 3072: Reworded multiple-document-handling definition,
    since it also applies to Jobs with a single Document and is the
    only interoperable way to request uncollated copies.
 o  Errata ID 3365: Fixed bad 'nameWithLanguage' maximum length by
    referencing the 'nameWithoutLanguage' section (i.e.,
    Section 5.1.3.1).
 o  Errata ID 4173: Fixed range of vendor operation codes (0x4000 to
    0x7fff).
 o  Updated obsoleted RFC references.
 o  Changed the IPP/1.1 Implementor's Guide reference to RFC 3196.
 o  Updated Create-Job, Send-Document, and Send-URI to RECOMMENDED.
 o  Incorporated 'collection' attribute content from RFC 3382.
 o  Obsoleted all attributes and values defined in RFC 3381, as they
    do not interact well with the "finishings" attribute and have
    never been widely implemented.
 o  Deprecated the Purge-Jobs and Restart-Job operations, which
    destroy accounting information.

Sweet & McDonald Standards Track [Page 187] RFC 8011 IPP/1.1: Model and Semantics January 2017

 o  Dropped type3 registration procedures.
 o  Changed the vendor attribute and keyword naming recommendations to
    use SMI Private Enterprise Numbers ("smiNNN-foo") instead of
    domain names.
 o  Split READ-ONLY Job Description and Printer Description attributes
    into Job Status and Printer Status attributes to match the current
    IANA IPP registry organization.
 o  Referenced all IETF and PWG IPP standards.
 o  Updated OPTIONAL operations, attributes, and values to RECOMMENDED
    for consistency with IPP 2.0, IPP Everywhere, and the IPP
    Implementor's Guide v2.0.
 o  Removed the appendix on media names.  Readers are directed to
    "PWG Media Standardized Names 2.0 (MSN2)" [PWG5101.1].

11. References

11.1. Normative References

 [ASME-Y14.1M]
            ASME Y14.1M-2012, "Metric Drawing Sheet Size and Format",
            March 2013.
 [ISO10175] ISO/IEC 10175, "Information technology -- Text and office
            systems -- Document Printing Application (DPA) -- Part 1:
            Abstract service definition and procedures",
            September 1996.
 [ISO10646] ISO/IEC 10646:2014, JTC1/SC2, "Information technology --
            Universal Coded Character Set (UCS)", September 2014.
 [ISO8859-1]
            ISO/IEC 8859-1:1998, "Information technology -- 8-bit
            single-byte coded graphic character sets -- Part 1: Latin
            alphabet No. 1", April 1998.
 [PWG5100.1]
            Sweet, M., "IPP Finishings 2.0 (FIN)", December 2014,
            <http://ftp.pwg.org/pub/pwg/candidates/
            cs-ippfinishings20-20141219-5100.1.pdf>.

Sweet & McDonald Standards Track [Page 188] RFC 8011 IPP/1.1: Model and Semantics January 2017

 [PWG5100.11]
            Hastings, T. and D. Fullman, "Internet Printing Protocol
            (IPP): Job and Printer Extensions -- Set 2 (JPS2)",
            October 2010, <http://ftp.pwg.org/pub/pwg/candidates/
            cs-ippjobprinterext10-20101030-5100.11.pdf>.
 [PWG5100.12]
            Sweet, M. and I. McDonald, "IPP Version 2.0, 2.1, and
            2.2", October 2015, <http://ftp.pwg.org/pub/pwg/standards/
            std-ipp20-20151030-5100.12.pdf>.
 [PWG5100.13]
            Sweet, M., McDonald, I., and P. Zehler, "IPP: Job and
            Printer Extensions -- Set 3 (JPS3)", July 2012,
            <http://ftp.pwg.org/pub/pwg/candidates/
            cs-ippjobprinterext3v10-20120727-5100.13.pdf>.
 [PWG5100.14]
            Sweet, M., McDonald, I., Mitchell, A., and J. Hutchings,
            "IPP Everywhere", January 2013,
            <http://ftp.pwg.org/pub/pwg/candidates/
            cs-ippeve10-20130128-5100.14.pdf>.
 [PWG5100.15]
            Sweet, M., "IPP FaxOut Service", June 2014,
            <http://ftp.pwg.org/pub/pwg/candidates/
            cs-ippfaxout10-20140618-5100.15.pdf>.
 [PWG5100.16]
            Sweet, M., "IPP Transaction-Based Printing Extensions",
            November 2013, <http://ftp.pwg.org/pub/pwg/candidates/
            cs-ipptrans10-20131108-5100.16.pdf>.
 [PWG5100.17]
            Zehler, P. and M. Sweet, "IPP Scan Service (SCAN)",
            September 2014, <http://ftp.pwg.org/pub/pwg/candidates/
            cs-ippscan10-20140918-5100.17.pdf>.
 [PWG5100.18]
            Sweet, M. and I. McDonald, "IPP Shared Infrastructure
            Extensions (INFRA)", June 2015,
            <http://ftp.pwg.org/pub/pwg/candidates/
            cs-ippinfra10-20150619-5100.18.pdf>.
 [PWG5100.19]
            Kennedy, S., "IPP Implementor's Guide v2.0 (IG)",
            August 2015, <http://ftp.pwg.org/pub/pwg/candidates/
            cs-ippig20-20150821-5100.19.pdf>.

Sweet & McDonald Standards Track [Page 189] RFC 8011 IPP/1.1: Model and Semantics January 2017

 [PWG5100.2]
            Hastings, T. and R. Bergman, "Internet Printing Protocol
            (IPP): "output-bin" attribute extension", February 2001,
            <http://ftp.pwg.org/pub/pwg/candidates/
            cs-ippoutputbin10-20010207-5100.2.pdf>.
 [PWG5100.3]
            Ocke, K. and T. Hastings, "Internet Printing Protocol
            (IPP): Production Printing Attributes -- Set1",
            February 2001, <http://ftp.pwg.org/pub/pwg/candidates/
            cs-ippprodprint10-20010212-5100.3.pdf>.
 [PWG5100.5]
            Carney, D., Hastings, T., and P. Zehler, "Standard for The
            Internet Printing Protocol (IPP): Document Object",
            October 2003, <http://ftp.pwg.org/pub/pwg/candidates/
            cs-ippdocobject10-20031031-5100.5.pdf>.
 [PWG5100.6]
            Zehler, P., Herriot, R., and K. Ocke, "Standard for The
            Internet Printing Protocol (IPP): Page Overrides",
            October 2003, <http://ftp.pwg.org/pub/pwg/candidates/
            cs-ipppageoverride10-20031031-5100.6.pdf>.
 [PWG5100.7]
            Hastings, T. and P. Zehler, "Standard for The Internet
            Printing Protocol (IPP): Job Extensions", October 2003,
            <http://ftp.pwg.org/pub/pwg/candidates/
            cs-ippjobext10-20031031-5100.7.pdf>.
 [PWG5100.8]
            Carney, D. and H. Lewis, "Standard for Internet Printing
            Protocol (IPP): "-actual" attributes", March 2003,
            <http://ftp.pwg.org/pub/pwg/candidates/
            cs-ippactuals10-20030313-5100.8.pdf>.
 [PWG5100.9]
            McDonald, I. and C. Whittle, "Internet Printing Protocol
            (IPP): Printer State Extensions v1.0", July 2009,
            <http://ftp.pwg.org/pub/pwg/candidates/
            cs-ippstate10-20090731-5100.9.pdf>.
 [PWG5101.1]
            Sweet, M., Bergman, R., and T. Hastings, "PWG Media
            Standardized Names 2.0 (MSN2)", March 2013,
            <http://ftp.pwg.org/pub/pwg/candidates/
            cs-pwgmsn20-20130328-5101.1.pdf>.

Sweet & McDonald Standards Track [Page 190] RFC 8011 IPP/1.1: Model and Semantics January 2017

 [RFC20]    Cerf, V., "ASCII format for network interchange", STD 80,
            RFC 20, DOI 10.17487/RFC0020, October 1969,
            <http://www.rfc-editor.org/info/rfc20>.
 [RFC793]   Postel, J., "Transmission Control Protocol", STD 7,
            RFC 793, DOI 10.17487/RFC0793, September 1981,
            <http://www.rfc-editor.org/info/rfc793>.
 [RFC1035]  Mockapetris, P., "Domain names - implementation and
            specification", STD 13, RFC 1035, DOI 10.17487/RFC1035,
            November 1987, <http://www.rfc-editor.org/info/rfc1035>.
 [RFC1951]  Deutsch, P., "DEFLATE Compressed Data Format Specification
            version 1.3", RFC 1951, DOI 10.17487/RFC1951, May 1996,
            <http://www.rfc-editor.org/info/rfc1951>.
 [RFC1952]  Deutsch, P., "GZIP file format specification version 4.3",
            RFC 1952, DOI 10.17487/RFC1952, May 1996,
            <http://www.rfc-editor.org/info/rfc1952>.
 [RFC1977]  Schryver, V., "PPP BSD Compression Protocol", RFC 1977,
            DOI 10.17487/RFC1977, August 1996,
            <http://www.rfc-editor.org/info/rfc1977>.
 [RFC2046]  Freed, N. and N. Borenstein, "Multipurpose Internet Mail
            Extensions (MIME) Part Two: Media Types", RFC 2046,
            DOI 10.17487/RFC2046, November 1996,
            <http://www.rfc-editor.org/info/rfc2046>.
 [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
            Requirement Levels", BCP 14, RFC 2119,
            DOI 10.17487/RFC2119, March 1997,
            <http://www.rfc-editor.org/info/rfc2119>.
 [RFC2818]  Rescorla, E., "HTTP Over TLS", RFC 2818,
            DOI 10.17487/RFC2818, May 2000,
            <http://www.rfc-editor.org/info/rfc2818>.
 [RFC3196]  Hastings, T., Manros, C., Zehler, P., Kugler, C., and H.
            Holst, "Internet Printing Protocol/1.1: Implementor's
            Guide", RFC 3196, DOI 10.17487/RFC3196, November 2001,
            <http://www.rfc-editor.org/info/rfc3196>.
 [RFC3380]  Hastings, T., Herriot, R., Kugler, C., and H. Lewis,
            "Internet Printing Protocol (IPP): Job and Printer Set
            Operations", RFC 3380, DOI 10.17487/RFC3380,
            September 2002, <http://www.rfc-editor.org/info/rfc3380>.

Sweet & McDonald Standards Track [Page 191] RFC 8011 IPP/1.1: Model and Semantics January 2017

 [RFC3510]  Herriot, R. and I. McDonald, "Internet Printing
            Protocol/1.1: IPP URL Scheme", RFC 3510,
            DOI 10.17487/RFC3510, April 2003,
            <http://www.rfc-editor.org/info/rfc3510>.
 [RFC3629]  Yergeau, F., "UTF-8, a transformation format of
            ISO 10646", STD 63, RFC 3629, DOI 10.17487/RFC3629,
            November 2003, <http://www.rfc-editor.org/info/rfc3629>.
 [RFC3805]  Bergman, R., Lewis, H., and I. McDonald, "Printer MIB v2",
            RFC 3805, DOI 10.17487/RFC3805, June 2004,
            <http://www.rfc-editor.org/info/rfc3805>.
 [RFC3986]  Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
            Resource Identifier (URI): Generic Syntax", STD 66,
            RFC 3986, DOI 10.17487/RFC3986, January 2005,
            <http://www.rfc-editor.org/info/rfc3986>.
 [RFC3995]  Herriot, R. and T. Hastings, "Internet Printing Protocol
            (IPP): Event Notifications and Subscriptions", RFC 3995,
            DOI 10.17487/RFC3995, March 2005,
            <http://www.rfc-editor.org/info/rfc3995>.
 [RFC3996]  Herriot, R., Hastings, T., and H. Lewis, "Internet
            Printing Protocol (IPP): The 'ippget' Delivery Method for
            Event Notifications", RFC 3996, DOI 10.17487/RFC3996,
            March 2005, <http://www.rfc-editor.org/info/rfc3996>.
 [RFC3998]  Kugler, C., Lewis, H., and T. Hastings, Ed., "Internet
            Printing Protocol (IPP): Job and Printer Administrative
            Operations", RFC 3998, DOI 10.17487/RFC3998, March 2005,
            <http://www.rfc-editor.org/info/rfc3998>.
 [RFC5051]  Crispin, M., "i;unicode-casemap - Simple Unicode Collation
            Algorithm", RFC 5051, DOI 10.17487/RFC5051, October 2007,
            <http://www.rfc-editor.org/info/rfc5051>.
 [RFC5234]  Crocker, D., Ed., and P. Overell, "Augmented BNF for
            Syntax Specifications: ABNF", STD 68, RFC 5234,
            DOI 10.17487/RFC5234, January 2008,
            <http://www.rfc-editor.org/info/rfc5234>.
 [RFC5246]  Dierks, T. and E. Rescorla, "The Transport Layer Security
            (TLS) Protocol Version 1.2", RFC 5246,
            DOI 10.17487/RFC5246, August 2008,
            <http://www.rfc-editor.org/info/rfc5246>.

Sweet & McDonald Standards Track [Page 192] RFC 8011 IPP/1.1: Model and Semantics January 2017

 [RFC5646]  Phillips, A., Ed., and M. Davis, Ed., "Tags for
            Identifying Languages", BCP 47, RFC 5646,
            DOI 10.17487/RFC5646, September 2009,
            <http://www.rfc-editor.org/info/rfc5646>.
 [RFC6838]  Freed, N., Klensin, J., and T. Hansen, "Media Type
            Specifications and Registration Procedures", BCP 13,
            RFC 6838, DOI 10.17487/RFC6838, January 2013,
            <http://www.rfc-editor.org/info/rfc6838>.
 [RFC7230]  Fielding, R., Ed., and J. Reschke, Ed., "Hypertext
            Transfer Protocol (HTTP/1.1): Message Syntax and Routing",
            RFC 7230, DOI 10.17487/RFC7230, June 2014,
            <http://www.rfc-editor.org/info/rfc7230>.
 [RFC7472]  McDonald, I. and M. Sweet, "Internet Printing Protocol
            (IPP) over HTTPS Transport Binding and the 'ipps' URI
            Scheme", RFC 7472, DOI 10.17487/RFC7472, March 2015,
            <http://www.rfc-editor.org/info/rfc7472>.
 [RFC7612]  Fleming, P. and I. McDonald, "Lightweight Directory Access
            Protocol (LDAP): Schema for Printer Services", RFC 7612,
            DOI 10.17487/RFC7612, June 2015,
            <http://www.rfc-editor.org/info/rfc7612>.
 [RFC7616]  Shekh-Yusef, R., Ed., Ahrens, D., and S. Bremer, "HTTP
            Digest Access Authentication", RFC 7616,
            DOI 10.17487/RFC7616, September 2015,
            <http://www.rfc-editor.org/info/rfc7616>.
 [RFC7617]  Reschke, J., "The 'Basic' HTTP Authentication Scheme",
            RFC 7617, DOI 10.17487/RFC7617, September 2015,
            <http://www.rfc-editor.org/info/rfc7617>.
 [RFC8010]  Sweet, M. and I. McDonald, "Internet Printing
            Protocol/1.1: Encoding and Transport", RFC 8010,
            DOI 10.17487/RFC8010, January 2017,
            <http://www.rfc-editor.org/info/rfc8010>.

Sweet & McDonald Standards Track [Page 193] RFC 8011 IPP/1.1: Model and Semantics January 2017

11.2. Informative References

 [HTPP]     Barnett, J., Carter, K., and R. deBry, "Internet Print
            Protocol Proposal: HTPP -- Hypertext Print Protocol
            (HTPP/1.0 Initial Draft)", October 1996,
            <ftp://ftp.pwg.org/pub/pwg/ipp/historic/htpp/
            overview.ps.gz>.
 [IANA-CS]  IANA, "Registry of Coded Character Sets",
            <http://www.iana.org/assignments/character-sets/>.
 [IANA-MT]  IANA, "Media Types",
            <http://www.iana.org/assignments/media-types/>.
 [IANA-PEN]
            IANA, "Private Enterprise Numbers",
            <http://www.iana.org/assignments/enterprise-numbers/>.
 [ISO32000] "Document management -- Portable document format --
            Part 1: PDF 1.7", July 2008, <http://www.adobe.com/
            devnet/acrobat/pdfs/PDF32000_2008.pdf>.
 [LDPA]     Isaacson, S., Taylor, D., MacKay, M., Zehler, P.,
            Hastings, T., and C. Manros, "LDPA - Lightweight Document
            Printing Application", Proposed Internet-Draft,
            October 1996, <ftp://ftp.pwg.org/pub/pwg/ipp/
            historic/ldpa/ldpa8.pdf.gz>.
 [P1387.4]  Kirk, M., "POSIX Systems Administration - Part 4: Printing
            Interfaces, POSIX 1387.4 D8", 1998.
 [PSIS]     Herriot, R., Ed., "X/Open: A Printing System
            Interoperability Specification (PSIS)", August 1995.
 [PWG-IPP-WG]
            IEEE-ISTO Printer Working Group, "Internet Printing
            Protocol Workgroup", <http://www.pwg.org/ipp>.
 [RFC959]   Postel, J. and J. Reynolds, "File Transfer Protocol",
            STD 9, RFC 959, DOI 10.17487/RFC0959, October 1985,
            <http://www.rfc-editor.org/info/rfc959>.
 [RFC1179]  McLaughlin, L., "Line printer daemon protocol", RFC 1179,
            DOI 10.17487/RFC1179, August 1990,
            <http://www.rfc-editor.org/info/rfc1179>.

Sweet & McDonald Standards Track [Page 194] RFC 8011 IPP/1.1: Model and Semantics January 2017

 [RFC1738]  Berners-Lee, T., Masinter, L., and M. McCahill, "Uniform
            Resource Locators (URL)", RFC 1738, DOI 10.17487/RFC1738,
            December 1994, <http://www.rfc-editor.org/info/rfc1738>.
 [RFC2565]  Herriot, R., Ed., Butler, S., Moore, P., and R. Turner,
            "Internet Printing Protocol/1.0: Encoding and Transport",
            RFC 2565, DOI 10.17487/RFC2565, April 1999,
            <http://www.rfc-editor.org/info/rfc2565>.
 [RFC2566]  deBry, R., Hastings, T., Herriot, R., Isaacson, S., and P.
            Powell, "Internet Printing Protocol/1.0: Model and
            Semantics", RFC 2566, DOI 10.17487/RFC2566, April 1999,
            <http://www.rfc-editor.org/info/rfc2566>.
 [RFC2567]  Wright, F., "Design Goals for an Internet Printing
            Protocol", RFC 2567, DOI 10.17487/RFC2567, April 1999,
            <http://www.rfc-editor.org/info/rfc2567>.
 [RFC2568]  Zilles, S., "Rationale for the Structure of the Model and
            Protocol for the Internet Printing Protocol", RFC 2568,
            DOI 10.17487/RFC2568, April 1999,
            <http://www.rfc-editor.org/info/rfc2568>.
 [RFC2569]  Herriot, R., Ed., Hastings, T., Jacobs, N., and J. Martin,
            "Mapping between LPD and IPP Protocols", RFC 2569,
            DOI 10.17487/RFC2569, April 1999,
            <http://www.rfc-editor.org/info/rfc2569>.
 [RFC2579]  McCloghrie, K., Ed., Perkins, D., Ed., and J.
            Schoenwaelder, Ed., "Textual Conventions for SMIv2",
            STD 58, RFC 2579, DOI 10.17487/RFC2579, April 1999,
            <http://www.rfc-editor.org/info/rfc2579>.
 [RFC2978]  Freed, N. and J. Postel, "IANA Charset Registration
            Procedures", BCP 19, RFC 2978, DOI 10.17487/RFC2978,
            October 2000, <http://www.rfc-editor.org/info/rfc2978>.
 [RFC3239]  Kugler, C., Lewis, H., and T. Hastings, "Internet Printing
            Protocol (IPP): Requirements for Job, Printer, and Device
            Administrative Operations", RFC 3239,
            DOI 10.17487/RFC3239, February 2002,
            <http://www.rfc-editor.org/info/rfc3239>.
 [RFC3997]  Hastings, T., Ed., deBry, R., and H. Lewis, "Internet
            Printing Protocol (IPP): Requirements for IPP
            Notifications", RFC 3997, DOI 10.17487/RFC3997,
            March 2005, <http://www.rfc-editor.org/info/rfc3997>.

Sweet & McDonald Standards Track [Page 195] RFC 8011 IPP/1.1: Model and Semantics January 2017

 [RFC4122]  Leach, P., Mealling, M., and R. Salz, "A Universally
            Unique IDentifier (UUID) URN Namespace", RFC 4122,
            DOI 10.17487/RFC4122, July 2005,
            <http://www.rfc-editor.org/info/rfc4122>.
 [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
            IANA Considerations Section in RFCs", BCP 26, RFC 5226,
            DOI 10.17487/RFC5226, May 2008,
            <http://www.rfc-editor.org/info/rfc5226>.
 [RFC6068]  Duerst, M., Masinter, L., and J. Zawinski, "The 'mailto'
            URI Scheme", RFC 6068, DOI 10.17487/RFC6068, October 2010,
            <http://www.rfc-editor.org/info/rfc6068>.
 [RFC7525]  Sheffer, Y., Holz, R., and P. Saint-Andre,
            "Recommendations for Secure Use of Transport Layer
            Security (TLS) and Datagram Transport Layer Security
            (DTLS)", BCP 195, RFC 7525, DOI 10.17487/RFC7525,
            May 2015, <http://www.rfc-editor.org/info/rfc7525>.
 [SWP]      Moore, P. and S. Butler, "Simple Web Printing (SWP/1.0)",
            May 1997, <ftp://ftp.pwg.org/pub/pwg/ipp/new_PRO/
            swp9705.pdf>.

Sweet & McDonald Standards Track [Page 196] RFC 8011 IPP/1.1: Model and Semantics January 2017

Appendix A. Formats for IPP Registration Proposals

 In order to propose an IPP extension for registration, the proposer
 must submit an application to IANA by email to "iana@iana.org" or by
 filling out the appropriate form on the IANA web pages
 (http://www.iana.org).  This section specifies the required
 information and the formats for proposing registrations of extensions
 to IPP as provided in Section 7 for:
 1.  attributes
 2.  type2 'keyword' attribute values
 3.  type2 'enum' attribute values
 4.  operations
 5.  status-code values

A.1. Attribute Registration

 Type of registration: attribute
 Proposed keyword name of this attribute:
 Types of attributes (Document Description, Document Status, Document
 Template, Event Notifications, Job Description, Job Status, Job
 Template, Operation, Printer Description, Printer Status,
 Subscription Description, Subscription Status, Subscription
 Template):
 Operations to be used if the attribute is an operation attribute:
 Object (Document, Job, Printer, Subscription, etc. if bound to an
 object):
 Attribute syntax(es) (include '1setOf' and range; see Section 5.2):
 If attribute syntax is 'keyword' or 'enum', is it type1 or type2?
 If this is a Printer attribute, MAY the value returned depend on
 "document-format"?  (See Section 7.2.)
 If this is a Job Template attribute, how does its specification
 depend on the value of the "multiple-document-handling" attribute?

Sweet & McDonald Standards Track [Page 197] RFC 8011 IPP/1.1: Model and Semantics January 2017

 Specification of this attribute (follow the style of Section 5.2):
 Name of proposer:
 Email address of proposer:
 Note: For attributes, the IPP Designated Expert will be the point of
 contact and change controller for the approved registration
 specification, if any maintenance of the registration specification
 is needed.

A.2. type2 'keyword' Attribute Value Registration

 Type of registration: type2 keyword attribute value
 Name of attribute to which this keyword specification is to be added:
 Proposed keyword name of this 'keyword' value:
 Specification of this 'keyword' value (follow the style of
 Section 5.1.4):
 Name of proposer:
 Email address of proposer:
 Note: For type2 keywords, the Designated Expert will be the point of
 contact and change controller for the approved registration
 specification, if any maintenance of the registration specification
 is needed.

A.3. type2 'enum' Attribute Value Registration

 Type of registration: type2 enum attribute value
 Name of attribute to which this enum specification is to be added:
 Keyword symbolic name of this enum value:
 Numeric value (to be assigned by the IPP Designated Expert in
 consultation with IANA):
 Specification of this enum value (follow the style of Section 5.1.5):
 Name of proposer:
 Email address of proposer:

Sweet & McDonald Standards Track [Page 198] RFC 8011 IPP/1.1: Model and Semantics January 2017

 Note: For type2 enums, the Designated Expert will be the point of
 contact and change controller for the approved registration
 specification, if any maintenance of the registration specification
 is needed.

A.4. Operation Registration

 Type of registration: operation
 Proposed name of this operation:
 Numeric "operation-id" value according to Section 5.4.15 (to be
 assigned by the IPP Designated Expert in consultation with IANA):
 Object Target (Document, Job, Printer, Subscription, etc. that
 operation is upon):
 Specification of this operation (follow the style of Section 4):
 Name of proposer:
 Email address of proposer:
 Note: For operations, the IPP Designated Expert will be the point of
 contact and change controller for the approved registration
 specification, if any maintenance of the registration specification
 is needed.

A.5. Status-Code Registration

 Type of registration: status-code
 Keyword symbolic name of this status-code value:
 Numeric value (to be assigned by the IPP Designated Expert in
 consultation with IANA):
 Operations that this status-code can be used with:
 Specification of this status-code (follow the style of Appendix B):
 Name of proposer:
 Email address of proposer:

Sweet & McDonald Standards Track [Page 199] RFC 8011 IPP/1.1: Model and Semantics January 2017

 Note: For status-code values, the Designated Expert will be the point
 of contact and change controller for the approved registration
 specification, if any maintenance of the registration specification
 is needed.

Appendix B. Status-Code Values and Suggested Status-Code Messages

 This section defines status-code enum keywords and values that are
 used to provide semantic information on the results of an operation
 request.  Each operation response MUST include a status-code.  The
 response MAY also contain a status message that provides a short
 textual description of the status.  The status-code is intended for
 use by automata, and the status message is intended for the human
 End User.
 The prefix of the status keyword defines the class of response as
 follows:
 "informational" - Request received, continuing process
 "successful" - The action was successfully received, understood, and
 accepted
 "redirection" - Further action is taken in order to complete the
 request
 "client-error" - The request contains bad syntax or cannot be
 fulfilled
 "server-error" - The IPP object failed to fulfill an apparently valid
 request
 As with type2 enums, IPP status-code values are extensible.
 Regardless of whether all status-code values are recognized, IPP
 Clients MUST understand the class of any status-code, as indicated by
 the prefix, and treat any unrecognized response as being equivalent
 to the first status-code of that class, with the exception that an
 unrecognized response MUST NOT be cached.  For example, if an
 unrecognized status-code of 'client-error-xxx-yyy' is received by the
 Client, it can safely assume that there was something wrong with its
 request and treat the response as if it had received a
 'client-error-bad-request' status-code.  The name of the enum is the
 suggested status message for US English.
 See [PWG5100.19] for guidelines on presenting status messages to
 End Users.

Sweet & McDonald Standards Track [Page 200] RFC 8011 IPP/1.1: Model and Semantics January 2017

 The status-code values range from 0x0000 to 0x7fff.  The value ranges
 for each status-code class are as follows:
 "successful" - 0x0000 to 0x00ff
 "informational" - 0x0100 to 0x01ff
 "redirection" - 0x0300 to 0x03ff
 "client-error" - 0x0400 to 0x04ff
 "server-error" - 0x0500 to 0x05ff
 The top half (128 values) of each range (0x0n80 to 0x0nff, for n = 0
 to 5) is reserved for vendor use within each status-code class.
 Values 0x0600 to 0x7fff are reserved for future assignment by
 Standards Track documents and MUST NOT be used.

B.1. Status-Code Values

 Each status-code is described below.  Appendix B.2 contains a table
 that indicates which status-code values apply to which operations.
 The Implementor's Guides [RFC3196] [PWG5100.19] provide guidance for
 processing IPP attributes for all operations, including status-code
 values.

B.1.1. Informational

 This class of status-code values indicates a provisional response and
 is to be used for informational purposes only.
 There are no values defined in this document for this class of
 status-code values.

B.1.2. Successful Status-Code Values

 This class of status-code values indicates that the Client's request
 was successfully received, understood, and accepted.

B.1.2.1. successful-ok (0x0000)

 The request has succeeded, and no request attributes were substituted
 or ignored.  In the case of a response to a Job Creation request, the
 'successful-ok' status-code indicates that the request was
 successfully received and validated, and that the Job object has been
 created; it does not indicate that the Job has been processed.  The
 transition of the Job object into the 'completed' state is the only
 indicator that the Job has been printed.

Sweet & McDonald Standards Track [Page 201] RFC 8011 IPP/1.1: Model and Semantics January 2017

B.1.2.2. successful-ok-ignored-or-substituted-attributes (0x0001)

 The request has succeeded, but some supplied (1) attributes were
 ignored or (2) unsupported values were substituted with supported
 values or were ignored in order to perform the operation without
 rejecting it.  Unsupported attributes, attribute syntaxes, or values
 MUST be returned in the Unsupported Attributes group of the response
 for all operations.  There is an exception to this rule for the query
 operations Get-Printer-Attributes, Get-Jobs, and Get-Job-Attributes
 for the "requested-attributes" operation attribute only.  When the
 supplied values of the "requested-attributes" operation attribute are
 requesting attributes that are not supported, the IPP object SHOULD
 return the "requested-attributes" operation attribute in the
 Unsupported Attributes group of the response (with the unsupported
 values only).  See Sections 4.1.7 and 4.2.1.2.

B.1.2.3. successful-ok-conflicting-attributes (0x0002)

 The request has succeeded, but some supplied attribute values
 conflicted with the values of other supplied attributes.  Either
 (1) these conflicting values were substituted with (supported) values
 or (2) the attributes were removed in order to process the Job
 without rejecting it.  Attributes or values that conflict with other
 attributes and have been substituted or ignored MUST be returned in
 the Unsupported Attributes group of the response for all operations
 as supplied by the Client.  See Sections 4.1.7 and 4.2.1.2.

B.1.3. Redirection Status-Code Values

 This class of status-code values indicates that further action needs
 to be taken to fulfill the request.
 There are no values defined in this document for this class of
 status-code values.

B.1.4. Client Error Status-Code Values

 This class of status-code values is intended for cases in which the
 Client seems to have erred.  The IPP object SHOULD return a message
 containing an explanation of the error situation and whether it is a
 temporary or permanent condition.

Sweet & McDonald Standards Track [Page 202] RFC 8011 IPP/1.1: Model and Semantics January 2017

B.1.4.1. client-error-bad-request (0x0400)

 The request could not be understood by the IPP object due to
 malformed syntax (such as the value of a fixed-length attribute whose
 length does not match the prescribed length for that attribute -- see
 the Implementor's Guides [RFC3196] [PWG5100.19]).  The IPP
 application SHOULD NOT repeat the request without modifications.

B.1.4.2. client-error-forbidden (0x0401)

 The IPP object understood the request but is refusing to fulfill it.
 Additional authentication information or authorization credentials
 will not help, and the request SHOULD NOT be repeated.  This
 status-code is commonly used when the IPP object does not wish to
 reveal exactly why the request has been refused or when no other
 response is applicable.

B.1.4.3. client-error-not-authenticated (0x0402)

 The request requires user authentication.  The IPP Client can repeat
 the request with suitable authentication information.  If the request
 already included authentication information, then this status-code
 indicates that authorization has been refused for those credentials.
 If this response contains the same challenge as the prior response
 and the user agent has already attempted authentication at least
 once, then the response message can contain relevant diagnostic
 information.  This status-code reveals more information than
 'client-error-forbidden'.

B.1.4.4. client-error-not-authorized (0x0403)

 The requester is not authorized to perform the request.  Additional
 authentication information or authorization credentials will not
 help, and the request SHOULD NOT be repeated.  This status-code is
 used when the IPP object wishes to reveal that the authentication
 information is understandable; however, the requester is explicitly
 not authorized to perform the request.  This status-code reveals more
 information than 'client-error-forbidden' and
 'client-error-not-authenticated'.

B.1.4.5. client-error-not-possible (0x0404)

 This status-code is used when the request is for something that
 cannot happen.  For example, there might be a request to cancel a Job
 that has already been canceled or aborted by the system.  The IPP
 Client SHOULD NOT repeat the request.

Sweet & McDonald Standards Track [Page 203] RFC 8011 IPP/1.1: Model and Semantics January 2017

B.1.4.6. client-error-timeout (0x0405)

 The Client did not produce a request within the time that the IPP
 object was prepared to wait.  For example, a Client issued a
 Create-Job operation and then, after a long period of time, issued a
 Send-Document operation; this error status-code was returned in
 response to the Send-Document request (see Section 4.3.1).  The IPP
 object might have been forced to clean up resources that had been
 held for the waiting additional Documents.  The IPP object was forced
 to close the Job, since the Client took too long.  The Client
 SHOULD NOT repeat the request without modifications.

B.1.4.7. client-error-not-found (0x0406)

 The IPP object has not found anything matching the request URI.  No
 indication is given of whether the condition is temporary or
 permanent.  For example, a Client with an old reference to a Job
 (a URI) tries to cancel the Job; however, in the meantime the Job
 might have been completed and all record of it at the Printer has
 been deleted.  This status-code, 'client-error-not-found', is
 returned indicating that the referenced Job cannot be found.  This
 error status-code is also used when a Client supplies a URI as a
 reference to the Document data in either a Print-URI or Send-URI
 operation but the Document cannot be found.
 In practice, an IPP application should avoid a "not found" situation
 by first querying and presenting a list of valid Printer URIs and Job
 URIs to the End User.

B.1.4.8. client-error-gone (0x0407)

 The requested object is no longer available, and no forwarding
 address is known.  This condition should be considered permanent.
 Clients with link-editing capabilities should delete references to
 the request URI after user approval.  If the IPP object does not know
 or has no facility to determine whether or not the condition is
 permanent, the status-code 'client-error-not-found' should be used
 instead.
 This response is primarily intended to assist the task of maintenance
 by notifying the recipient that the resource is intentionally
 unavailable and that the IPP object Administrator desires that remote
 links to that resource be removed.  It is not necessary to mark all
 permanently unavailable resources as "gone" or to keep the mark for
 any length of time -- that is left to the discretion of the IPP
 object Administrator and/or Printer implementation.

Sweet & McDonald Standards Track [Page 204] RFC 8011 IPP/1.1: Model and Semantics January 2017

B.1.4.9. client-error-request-entity-too-large (0x0408)

 The IPP object is refusing to process a request because the request
 entity is larger than the IPP object is willing or able to process.
 An IPP Printer returns this status-code when it limits the size of
 Print Jobs and it receives a Print Job that exceeds that limit or
 when the attributes are so many that their encoding causes the
 request entity to exceed IPP object capacity.

B.1.4.10. client-error-request-value-too-long (0x0409)

 The IPP object is refusing to service the request because one or more
 of the Client-supplied attributes have a variable-length value that
 is longer than the maximum length specified for that attribute.  The
 IPP object might not have sufficient resources (memory, buffers,
 etc.) to process (even temporarily), interpret, and/or ignore a value
 larger than the maximum length.  Another use of this error code is
 when the IPP object supports the processing of a large value that is
 less than the maximum length, but during the processing of the
 request as a whole, the object can pass the value onto some other
 system component that is not able to accept the large value.  For
 more details, see the Implementor's Guides [RFC3196] [PWG5100.19].
 Note: For attribute values that are URIs, this rare condition is only
 likely to occur when a Client has improperly submitted a request with
 long query information (e.g., an IPP application allows an End User
 to enter an invalid URI), when the Client has descended into a URI
 "black hole" of redirection (e.g., a redirected URI prefix that
 points to a suffix of itself), or when the IPP object is under attack
 by a Client attempting to exploit security holes present in some IPP
 objects using fixed-length buffers for reading or manipulating the
 request URI.

B.1.4.11. client-error-document-format-not-supported (0x040a)

 The IPP object is refusing to service the request because the
 Document data is in a format, as specified in the "document-format"
 operation attribute, that is not supported by the Printer.  This
 error is returned independent of the Client-supplied
 "ipp-attribute-fidelity" attribute.  The Printer MUST return this
 status-code, even if there are other Job Template attributes that are
 not supported as well, since this error is a bigger problem than with
 Job Template attributes.  See Sections 4.1.6.1, 4.1.7, and 4.2.1.1.

Sweet & McDonald Standards Track [Page 205] RFC 8011 IPP/1.1: Model and Semantics January 2017

B.1.4.12. client-error-attributes-or-values-not-supported (0x040b)

 In a Job Creation request, if the Printer does not support one or
 more attributes, attribute syntaxes, or attribute values supplied in
 the request and the Client supplied the "ipp-attribute-fidelity"
 operation attribute with the 'true' value, the Printer MUST return
 this status-code.  The Printer MUST also return in the Unsupported
 Attributes group all the attributes and/or values supplied by the
 Client that are not supported.  See Section 4.1.7.  Examples would be
 if the request indicates 'iso-a4' media but that media type is not
 supported by the Printer, or if the Client supplies a Job Template
 attribute and the attribute itself is not even supported by the
 Printer.  If the "ipp-attribute-fidelity" attribute is 'false', the
 Printer MUST ignore or substitute values for unsupported Job Template
 attributes and values rather than reject the request and return this
 status-code.
 For any operation where a Client requests attributes (such as a
 Get-Jobs, Get-Printer-Attributes, or Get-Job-Attributes operation),
 if the IPP object does not support one or more of the requested
 attributes, the IPP object simply ignores the unsupported requested
 attributes and processes the request as if they had not been
 supplied, rather than returning this status-code.  In this case,
 the IPP object MUST return the
 'successful-ok-ignored-or-substituted-attributes' status-code and
 SHOULD return the unsupported attributes as values of the
 "requested-attributes" operation attribute in the Unsupported
 Attributes group (see Appendix B.1.2.2).

B.1.4.13. client-error-uri-scheme-not-supported (0x040c)

 The scheme of the Client-supplied URI in a Print-URI or a Send-URI
 operation is not supported.  See Sections 4.1.6.1 and 4.1.7.

B.1.4.14. client-error-charset-not-supported (0x040d)

 For any operation, if the IPP Printer does not support the charset
 supplied by the Client in the "attributes-charset" operation
 attribute, the Printer MUST reject the operation and return this
 status-code, and any 'text' or 'name' attributes using the 'utf-8'
 charset (Section 4.1.4.1).  See Sections 4.1.6.1 and 4.1.7.

Sweet & McDonald Standards Track [Page 206] RFC 8011 IPP/1.1: Model and Semantics January 2017

B.1.4.15. client-error-conflicting-attributes (0x040e)

 The request is rejected because some attribute values conflicted with
 the values of other attributes that this document does not permit to
 be substituted or ignored.  The Printer MUST also return in the
 Unsupported Attributes group the conflicting attributes supplied by
 the Client.  See Sections 4.1.7 and 4.2.1.2.

B.1.4.16. client-error-compression-not-supported (0x040f)

 The IPP object is refusing to service the request because the
 Document data, as specified in the "compression" operation attribute,
 is compressed in a way that is not supported by the Printer.  This
 error is returned independent of the Client-supplied
 "ipp-attribute-fidelity" attribute.  The Printer MUST return this
 status-code, even if there are other Job Template attributes that are
 not supported as well, since this error is a bigger problem than with
 Job Template attributes.  See Sections 4.1.6.1, 4.1.7, and 4.2.1.1.

B.1.4.17. client-error-compression-error (0x0410)

 The IPP object is refusing to service the request because the
 Document data cannot be decompressed when using the algorithm
 specified by the "compression" operation attribute.  This error is
 returned independent of the Client-supplied "ipp-attribute-fidelity"
 attribute.  The Printer MUST return this status-code, even if there
 are Job Template attributes that are not supported as well, since
 this error is a bigger problem than with Job Template attributes.
 See Sections 4.1.7 and 4.2.1.1.

B.1.4.18. client-error-document-format-error (0x0411)

 The IPP object is refusing to service the request because the Printer
 encountered an error in the Document data while interpreting it.
 This error is returned independent of the Client-supplied
 "ipp-attribute-fidelity" attribute.  The Printer MUST return this
 status-code, even if there are Job Template attributes that are not
 supported as well, since this error is a bigger problem than with Job
 Template attributes.  See Sections 4.1.7 and 4.2.1.1.

B.1.4.19. client-error-document-access-error (0x0412)

 The IPP object is refusing to service the Print-URI or Send-URI
 request because the Printer encountered an access error while
 attempting to validate the accessibility of, or access to, the
 Document data specified in the "document-uri" operation attribute.
 The Printer MAY also return a specific Document access error code
 using the "document-access-error" operation attribute (see

Sweet & McDonald Standards Track [Page 207] RFC 8011 IPP/1.1: Model and Semantics January 2017

 Section 4.1.6.4).  This error is returned independent of the
 Client-supplied "ipp-attribute-fidelity" attribute.  The Printer MUST
 return this status-code, even if there are Job Template attributes
 that are not supported as well, since this error is a bigger problem
 than with Job Template attributes.  See Sections 4.1.6.1 and 4.1.7.

B.1.5. Server Error Status-Code Values

 This class of status-code values indicates cases in which the IPP
 object is aware that it has erred or is incapable of performing the
 request.  The IPP object SHOULD include a message containing an
 explanation of the error situation, and whether it is a temporary or
 permanent condition.

B.1.5.1. server-error-internal-error (0x0500)

 The IPP object encountered an unexpected condition that prevented it
 from fulfilling the request.  This error status-code differs from
 'server-error-temporary-error' in that it implies a more permanent
 type of internal error.  It also differs from
 'server-error-device-error' in that it implies an unexpected
 condition (unlike a paper-jam or out-of-toner problem, which is
 undesirable but expected).  This error status-code indicates that
 intervention by a knowledgeable human is probably required.

B.1.5.2. server-error-operation-not-supported (0x0501)

 The IPP object does not support the functionality required to fulfill
 the request.  This is the appropriate response when the IPP object
 does not recognize an operation or is not capable of supporting it.
 See Sections 4.1.6.1 and 4.1.7.

B.1.5.3. server-error-service-unavailable (0x0502)

 The IPP object is currently unable to handle the request due to
 temporary overloading or due to maintenance of the IPP object.  The
 implication is that this is a temporary condition that will be
 alleviated after some delay.  If known, the length of the delay can
 be indicated in the message.  If no delay is given, the IPP
 application should handle the response as it would for a
 'server-error-temporary-error' response.  If the condition is more
 permanent, the 'client-error-gone' or 'client-error-not-found' error
 status-code could be used.

Sweet & McDonald Standards Track [Page 208] RFC 8011 IPP/1.1: Model and Semantics January 2017

B.1.5.4. server-error-version-not-supported (0x0503)

 The IPP object does not support or refuses to support the IPP version
 that was supplied as the value of the "version-number" operation
 parameter in the request.  The IPP object is indicating that it is
 unable or unwilling to complete the request using the same major and
 minor version number as supplied in the request, other than with this
 error message.  The error response SHOULD contain a "status-message"
 attribute (see Section 4.1.6.2) describing why that version is not
 supported and what other versions are supported by that IPP object.
 See Sections 4.1.6.1, 4.1.7, and 4.1.8.
 The error response MUST identify in the "version-number" operation
 parameter the closest version number that the IPP object does
 support.  For example, if a Client supplies version '1.0' and an
 IPP/1.1 object supports version '1.0', then it responds with
 version '1.0' in all responses to such a request.  If the IPP/1.1
 object does not support version '1.0', then it should accept the
 request and respond with version '1.1' or can reject the request and
 respond with this error code and version '1.1'.  If a Client supplies
 version '1.2', the IPP/1.1 object should accept the request and
 return version '1.1' or can reject the request and respond with this
 error code and version '1.1'.  See Sections 4.1.8 and 5.3.14.

B.1.5.5. server-error-device-error (0x0504)

 A Printer error, such as a paper jam, occurs while the IPP object
 processes a Print or send operation.  The response contains the true
 Job status (the values of the "job-state" and "job-state-reasons"
 attributes).  Additional information can be returned in the OPTIONAL
 "job-state-message" attribute value or in the OPTIONAL status message
 that describes the error in more detail.  This error status-code is
 only returned in situations where the Printer is unable to accept the
 Job Creation request because of such a device error.  For example, if
 the Printer is unable to spool and can only accept one Job at a time,
 the reason it might reject a Job Creation request is that the Printer
 currently has a paper jam.  In many cases, however, where the Printer
 can accept the request even though the Printer has some error
 condition, the 'successful-ok' status-code will be returned.  In such
 a case, the Client would look at the returned Job object attributes
 or later query the Printer to determine its state and state reasons.

Sweet & McDonald Standards Track [Page 209] RFC 8011 IPP/1.1: Model and Semantics January 2017

B.1.5.6. server-error-temporary-error (0x0505)

 A temporary error such as a buffer-full write error, a memory
 overflow (i.e., the Document data exceeds the memory of the Printer),
 or a disk-full condition, occurs while the IPP Printer processes an
 operation.  The Client MAY try the unmodified request again at some
 later point in time with an expectation that the temporary internal
 error condition has been cleared.  Alternatively, as an
 implementation option, a Printer MAY delay the response until the
 temporary condition is cleared so that no error is returned.

B.1.5.7. server-error-not-accepting-jobs (0x0506)

 This is a temporary error indicating that the Printer is not
 currently accepting Jobs because the Administrator has set the value
 of the Printer's "printer-is-accepting-jobs" attribute to 'false' (by
 means outside the scope of this IPP/1.1 document).

B.1.5.8. server-error-busy (0x0507)

 This is a temporary error indicating that the Printer is too busy
 processing Jobs and/or other requests.  The Client SHOULD try the
 unmodified request again at some later point in time with an
 expectation that the temporary busy condition will have been cleared.

B.1.5.9. server-error-job-canceled (0x0508)

 This is an error indicating that the Job has been canceled by an
 Operator or the system while the Client was transmitting the data to
 the IPP Printer.  If a "job-id" attribute and a "job-uri" attribute
 had been created, then they are returned in the Print-Job,
 Send-Document, or Send-URI response as usual; otherwise, no "job-id"
 and "job-uri" attributes are returned in the response.

B.1.5.10. server-error-multiple-document-jobs-not-supported (0x0509)

 The IPP object does not support multiple Documents per Job, and a
 Client attempted to supply Document data with a second Send-Document
 or Send-URI operation.

Sweet & McDonald Standards Track [Page 210] RFC 8011 IPP/1.1: Model and Semantics January 2017

B.2. Status-Code Values for IPP Operations

 PJ = Print-Job, PU = Print-URI, CJ = Create-Job, SD = Send-Document,
 SU = Send-URI, V = Validate-Job, GA = Get-Job-Attributes and
 Get-Printer-Attributes, GJ = Get-Jobs, C = Cancel-Job
                                                IPP Operations
 IPP Status Keyword                       PJ PU CJ SD SU V GA GJ C
 ------------------                       -- -- -- -- -- - -- -- -
 successful-ok                            x  x  x  x  x  x x  x  x
 successful-ok-ignored-or-substituted-    x  x  x  x  x  x x  x  x
      attributes
 successful-ok-conflicting-attributes     x  x  x  x  x  x x  x  x
 client-error-bad-request                 x  x  x  x  x  x x  x  x
 client-error-forbidden                   x  x  x  x  x  x x  x  x
 client-error-not-authenticated           x  x  x  x  x  x x  x  x
 client-error-not-authorized              x  x  x  x  x  x x  x  x
 client-error-not-possible                x  x  x  x  x  x x  x  x
 client-error-timeout                              x  x
 client-error-not-found                   x  x  x  x  x  x x  x  x
 client-error-gone                        x  x  x  x  x  x x  x  x
 client-error-request-entity-too-large    x  x  x  x  x  x x  x  x
 client-error-request-value-too-long      x  x  x  x  x  x x  x  x
 client-error-document-format-not-        x  x     x  x  x x
      supported
 client-error-attributes-or-values-not-   x  x  x  x  x  x x  x  x
      supported
 client-error-uri-scheme-not-supported       x        x
 client-error-charset-not-supported       x  x  x  x  x  x x  x  x
 client-error-conflicting-attributes      x  x  x  x  x  x x  x  x
 client-error-compression-not-supported   x  x     x  x  x
 client-error-compression-error           x  x     x  x
 client-error-document-format-error       x  x     x  x
 client-error-document-access-error          x        x
 server-error-internal-error              x  x  x  x  x  x x  x  x
 server-error-operation-not-supported        x  x  x  x
 server-error-service-unavailable         x  x  x  x  x  x x  x  x
 server-error-version-not-supported       x  x  x  x  x  x x  x  x
 server-error-device-error                x  x  x  x  x
 server-error-temporary-error             x  x  x  x  x
 server-error-not-accepting-jobs          x  x  x        x
 server-error-busy                        x  x  x  x  x  x x  x  x
 server-error-job-canceled                x        x  x
 server-error-multiple-document-jobs-              x  x
        not-supported

Sweet & McDonald Standards Track [Page 211] RFC 8011 IPP/1.1: Model and Semantics January 2017

 HJ = Hold-Job, RJ = Release-Job, RS = Restart-Job,
 PP = Pause-Printer, RP = Resume-Printer, PJ = Purge-Jobs
                                          IPP Operations (cont.)
 IPP Status Keyword                       HJ RJ RS PP RP PJ
 ------------------                       -- -- -- -- -- --
 successful-ok                            x  x  x  x  x  x
 successful-ok-ignored-or-substituted-    x  x  x  x  x  x
      attributes
 successful-ok-conflicting-attributes     x  x  x  x  x  x
 client-error-bad-request                 x  x  x  x  x  x
 client-error-forbidden                   x  x  x  x  x  x
 client-error-not-authenticated           x  x  x  x  x  x
 client-error-not-authorized              x  x  x  x  x  x
 client-error-not-possible                x  x  x  x  x  x
 client-error-timeout
 client-error-not-found                   x  x  x  x  x  x
 client-error-gone                        x  x  x  x  x  x
 client-error-request-entity-too-large    x  x  x  x  x  x
 client-error-request-value-too-long      x  x  x  x  x  x
 client-error-document-format-not-
      supported
 client-error-attributes-or-values-not-   x  x  x  x  x  x
      supported
 client-error-uri-scheme-not-supported
 client-error-charset-not-supported       x  x  x  x  x  x
 client-error-conflicting-attributes      x  x  x  x  x  x
 client-error-compression-not-supported
 client-error-compression-error
 client-error-document-format-error
 client-error-document-access-error
 server-error-internal-error              x  x  x  x  x  x
 server-error-operation-not-supported     x  x  x  x  x  x
 server-error-service-unavailable         x  x  x  x  x  x
 server-error-version-not-supported       x  x  x  x  x  x
 server-error-device-error
 server-error-temporary-error             x  x  x  x  x  x
 server-error-not-accepting-jobs
 server-error-busy                        x  x  x  x  x  x
 server-error-job-canceled
 server-error-multiple-document-jobs-
        not-supported

Sweet & McDonald Standards Track [Page 212] RFC 8011 IPP/1.1: Model and Semantics January 2017

Appendix C. Processing IPP Attributes

 When submitting a Print Job to a Printer, the IPP Model allows a
 Client to supply operation and Job Template attributes along with the
 Document data.  These Job Template attributes in the Job Creation
 request affect the rendering, production, and finishing of the
 Documents in the Job.  Similar types of instructions can also be
 contained in the Document data itself.  In addition, the Printer has
 a set of attributes that describe what rendering and finishing
 processes are supported by that Printer.  This model, which allows
 for flexibility and power, also introduces the potential that
 Client-supplied attributes can conflict with either:
 o  what the implementation is capable of realizing (i.e., what the
    Printer supports), or
 o  the instructions embedded within the Document data itself.
 The following sections describe how these two types of conflicts are
 handled in the IPP Model.

C.1. Fidelity

 If there is a conflict between what the Client requests and what a
 Printer supports, the Client can request one of two possible
 conflict-handling mechanisms:
 1)  either reject the Job, since the Job cannot be processed exactly
     as specified, or
 2)  allow the Printer to make any changes necessary to proceed with
     processing the Job the best it can.
 In the first case, the Client is indicating the following to the
 Printer: "Print the Job exactly as specified with no exceptions, and
 if that can't be done, don't even bother printing the Job at all."
 In the second case, the Client is indicating the following to the
 Printer: "It is more important to make sure the Job is printed rather
 than be processed exactly as specified; just make sure the Job is
 printed even if some Client-supplied attributes need to be changed or
 ignored."
 The IPP Model accounts for this situation by introducing an
 "ipp-attribute-fidelity" attribute.

Sweet & McDonald Standards Track [Page 213] RFC 8011 IPP/1.1: Model and Semantics January 2017

 In a Job Creation request, "ipp-attribute-fidelity" is a boolean
 operation attribute that MAY be supplied by the Client.  The value
 'true' indicates that total fidelity to Client-supplied Job Template
 attributes and values is required.  The Client is requesting that the
 Job be printed exactly as specified, and if that is not possible,
 then the Job MUST be rejected rather than processed incorrectly.  The
 value 'false' indicates that a reasonable attempt to print the Job is
 acceptable.  If a Printer does not support some of the
 Client-supplied Job Template attributes or values, the Printer MUST
 ignore or replace them with supported values.  The Printer can choose
 to substitute the default value associated with that attribute or use
 some other supported value that is similar to the unsupported
 requested value.  For example, if a Client supplies a "media" value
 of 'na_letter_8.5x11in', the Printer can choose to substitute
 'iso_a4_210x297mm' rather than a default value of
 'na_personal_3.625x6.5in'.  If the Client does not supply the
 "ipp-attribute-fidelity" attribute, the Printer assumes a value of
 'false'.
 Each Printer implementation MUST support both types of "fidelity"
 printing (that is, whether the Client supplies a value of 'true' or
 'false'):
 o  If the Client supplies 'false' or does not supply the attribute,
    the Printer MUST always accept the request by ignoring unsupported
    Job Template attributes and by substituting unsupported values of
    supported Job Template attributes with supported values.
 o  If the Client supplies 'true', the Printer MUST reject the request
    if the Client supplies unsupported Job Template attributes.
 Since a Client can always query a Printer to find out exactly what is
 and is not supported, "ipp-attribute-fidelity" set to 'false' is
 useful when:
 1)  The End User uses a command line interface to request attributes
     that might not be supported.
 2)  In a GUI context, if the End User expects the Job might be moved
     to another Printer and prefers a suboptimal result to nothing
     at all.
 3)  The End User just wants something reasonable in lieu of nothing
     at all.

Sweet & McDonald Standards Track [Page 214] RFC 8011 IPP/1.1: Model and Semantics January 2017

C.2. Page Description Language (PDL) Override

 If there is a conflict between the value of an IPP Job Template
 attribute and a corresponding instruction in the Document data, the
 value of the IPP attribute SHOULD take precedence over the Document
 instruction.  Consider the case where a previously formatted file of
 Document data is sent to an IPP Printer.  In this case, if the Client
 supplies any attributes at Job submission time, the Client desires
 that those attributes override the embedded instructions.  Consider
 the case where a previously formatted Document has embedded in it
 commands to load 'iso-a4' media.  However, the Document is passed to
 an End User that only has access to a Printer with 'na-letter' media
 loaded.  That End User most likely wants to submit that Document to
 an IPP Printer with the "media" Job Template attribute set to
 'na-letter'.  Attributes supplied at Job submission time should take
 precedence over the embedded PDL instructions.  However, until
 companies that supply Document data interpreters allow a way for
 external IPP attributes to take precedence over embedded Job
 production instructions, a Printer might not be able to support the
 semantics that IPP attributes override the embedded instructions.
 The IPP Model accounts for this situation by introducing a
 "pdl-override-supported" attribute that describes the Printer's
 capabilities to override instructions embedded in the PDL data
 stream.  The value of the "pdl-override-supported" attribute is
 configured by means outside the scope of this IPP/1.1 document.
 This REQUIRED Printer attribute takes on the following values:
 o  'attempted': This value indicates that the Printer attempts to
    make the IPP attribute values take precedence over embedded
    instructions in the Document data; however, there is no guarantee.
 o  'not-attempted': This value indicates that the Printer makes no
    attempt to make the IPP attribute values take precedence over
    embedded instructions in the Document data.
 At Job processing time, an implementation that supports the value of
 'attempted' might do one of several different actions:
 1)  Generate an Output-Device-specific command sequence to realize
     the feature represented by the IPP attribute value.
 2)  Parse the Document data itself and replace the conflicting
     embedded instruction with a new embedded instruction that matches
     the intent of the IPP attribute value.

Sweet & McDonald Standards Track [Page 215] RFC 8011 IPP/1.1: Model and Semantics January 2017

 3)  Indicate to the Printer that external supplied attributes take
     precedence over embedded instructions and then pass the external
     IPP attribute values to the Document data interpreter.
 4)  Anything else that allows for the semantics that IPP attributes
     override embedded Document data instructions.
 Since 'attempted' does not offer any type of guarantee, even though a
 given Printer might not do a very "good" job of attempting to ensure
 that IPP attributes take a higher precedence over instructions
 embedded in the Document data, it would still be a conforming
 implementation.
 At Job processing time, an implementation that supports the value of
 'not-attempted' might do one of the following actions:
 1)  Simply prepend the Document data with the PDL instruction that
     corresponds to the Client-supplied PDL attribute, such that if
     the Document data also has the same PDL instruction it will
     override what the Printer prepended.  In other words, this
     implementation is using the same implementation semantics for the
     Client-supplied IPP attributes as for the Printer defaults.
 2)  Parse the Document data and replace the conflicting embedded
     instruction with a new embedded instruction that approximates,
     but does not match, the semantic intent of the IPP attribute
     value.
 Note: The "ipp-attribute-fidelity" attribute applies to the Printer's
 ability to either accept or reject other unsupported Job Template
 attributes.  In other words, if "ipp-attribute-fidelity" is set to
 'true', a Job is accepted if and only if the Client-supplied Job
 Template attributes and values are supported by the Printer.  Whether
 these attributes actually affect the processing of the Job when the
 Document data contains embedded instructions depends on the ability
 of the Printer to override the instructions embedded in the Document
 data with the semantics of the IPP attributes.  If the Document data
 attributes can be overridden ("pdl-override-supported" set to
 'attempted'), the Printer makes an attempt to use the IPP attributes
 when processing the Job.  If the Document data attributes cannot be
 overridden ("pdl-override-supported" set to 'not-attempted'), the
 Printer makes no attempt to override the embedded Document data
 instructions with the IPP attributes when processing the Job, and
 hence, the IPP attributes can fail to affect the Job processing and
 output when the corresponding instruction is embedded in the
 Document data.

Sweet & McDonald Standards Track [Page 216] RFC 8011 IPP/1.1: Model and Semantics January 2017

C.3. Using Job Template Attributes during Document Processing

 The Printer uses some of the Job's Job Template attributes during the
 processing of the Document data associated with that Job.  These
 include, but are not limited to, "orientation-requested",
 "number-up", "sides", "media", and "copies".  The processing of each
 Document in a Job object MUST follow the steps below.  These steps
 are intended only to identify when and how attributes are to be used
 in processing Document data; any alternative steps that accomplish
 the same effect can be used to implement this specification document.
 1.  Using the Client-supplied "document-format" attribute or some
     form of Document format detection algorithm (if the value of
     "document-format" is not specific enough), determine whether the
     Document data has already been formatted for printing.  If the
     Document data has been formatted, then go to step 2.  Otherwise,
     the Document data MUST be formatted.  The formatting detection
     algorithm is implementation defined and is not specified by this
     document.  The formatting of the Document data uses the
     "orientation-requested" attribute to determine how the formatted
     print data should be placed on an Input Page; see Section 5.2.10
     for details.
 2.  The Document data is a set of Input Pages in a known media type.
     The "page-ranges" attribute is used to select, as specified in
     Section 5.2.7, a sub-sequence of the pages in the print-stream
     that are to be processed and imaged.
 3.  The input for this step is a sequence of Input Pages.  This step
     is controlled by the "number-up" attribute.  If the value of
     "number-up" is N, then during the processing of the Input Pages
     each N Input Pages are positioned, as specified in Section 5.2.9,
     to create a single Impression.  If a given Document does not have
     N more Input Pages, then the completion of the Impression is
     controlled by the "multiple-document-handling" attribute as
     described in Section 5.2.4; when the value of this attribute is
     'single-document' or 'single-document-new-sheet', the Input Pages
     of Document data from subsequent Documents are used to complete
     the Impression.
 The size (scaling), position (translation), and rotation of the Input
 Pages on the Impression are implementation defined.  Note that during
 this process the Input Pages can be rendered to a form suitable for
 placing on the Impression; this rendering is controlled by the values
 of the "printer-resolution" and "print-quality" attributes as
 described in Sections 5.2.12 and 5.2.13.  In the case where N = 1,
 the Impression is nearly the same as the Input Page; the differences

Sweet & McDonald Standards Track [Page 217] RFC 8011 IPP/1.1: Model and Semantics January 2017

 would only be in the size, position, and rotation of the Input Page
 and/or any decoration, such as a frame for the page, that is added by
 the implementation.
 1.  The collection of Impressions is placed, in sequence, onto sides
     of the Media Sheets.  This placement is controlled by the "sides"
     attribute and the orientation of the Input Page, as described in
     Section 5.2.8.  The orientation of the Input Pages affects the
     orientation of the Impression; for example, if "number-up" equals
     2, then, typically, two portrait Input Pages become one landscape
     Impression.  Note that the placement of Impressions onto Media
     Sheets is also controlled by the "multiple-document-handling"
     attribute as described in Section 5.2.4.
 2.  The "copies" and "multiple-document-handling" attributes are used
     to determine how many copies of each Media Sheet are printed and
     in what order.  See Sections 5.2.4 and 5.2.5 for details.
 3.  When the correct number of copies are created, the Media Sheets
     are finished according to the values of the "finishings"
     attribute as described in Section 5.2.6.  Note that sometimes
     finishing processes can require manual intervention to perform
     the finishing processes on the copies, especially uncollated
     copies.  This document allows any or all of the processing steps
     to be performed automatically or manually, at the discretion of
     the Printer.

Appendix D. Generic Directory Schema

 This section defines a generic schema for an entry in a directory
 service.  Implementations of this schema are defined by "Lightweight
 Directory Access Protocol (LDAP): Schema for Printer Services"
 [RFC7612] and "IPP Everywhere" [PWG5100.14].  A directory service is
 a means by which service users can locate service providers.  In IPP
 environments, this means that IPP Printers can be registered (either
 automatically or with the help of an Administrator) as entries of
 type Printer in the directory using an implementation-specific
 mechanism such as entry attributes, entry type fields, specific
 branches, etc.  Directory Clients can search or browse for entries of
 type Printer.  Clients use the directory service to find entries
 based on naming, organizational contexts, or filtered searches on
 attribute values of entries.  For example, a Client can find all
 Printers in the "Local Department" context.  Authentication and
 authorization are also often part of a directory service so that an
 Administrator can place limits on End Users so that they are only
 allowed to find entries to which they have certain access rights.
 IPP itself does not require any specific directory service protocol
 or provider.

Sweet & McDonald Standards Track [Page 218] RFC 8011 IPP/1.1: Model and Semantics January 2017

 Note: Some directory implementations allow for the notion of
 "aliasing".  That is, one directory entry object can appear as
 multiple directory entry objects with different names for each
 object.  In each case, each alias refers to the same directory entry
 object, which refers to a single IPP Printer.
 The generic schema is a subset of IPP Printer Job Template and
 Printer Description attributes (Sections 5.2 and 5.4).  These
 attributes are identified as either RECOMMENDED or OPTIONAL for the
 directory entry itself.  This conformance labeling is NOT the same
 conformance labeling applied to the attributes of IPP Printer
 objects.  The conformance labeling in this appendix is intended to
 apply to directory templates and to IPP Printer implementations that
 subscribe by adding one or more entries to a directory.  RECOMMENDED
 attributes SHOULD be associated with each directory entry.  OPTIONAL
 attributes MAY be associated with the directory entry (if known or
 supported).  In addition, all directory entry attributes SHOULD
 reflect the current attribute values for the corresponding Printer.
 As much as possible, the names of attributes in directory schema and
 entries SHOULD be the same as the IPP Printer attribute names as
 shown.
 In order to bridge between the directory service and the IPP Printer,
 one of the RECOMMENDED directory entry attributes is the Printer's
 "printer-uri-supported" attribute.  The directory Client queries the
 "printer-uri-supported" attribute (or its equivalent) in the
 directory entry, and then the IPP Client addresses the IPP Printer
 using one of its URIs.  The "uri-security-supported" attribute
 identifies the protocol (if any) used to secure a channel.
 The attributes in Table 23 define the generic schema for directory
 entries of type Printer.
 +------------------------------------+-------------+----------------+
 | Attribute                          | Conformance | Section        |
 +------------------------------------+-------------+----------------+
 | charset-supported                  | OPTIONAL    | Section 5.4.18 |
 +------------------------------------+-------------+----------------+
 | color-supported                    | RECOMMENDED | Section 5.4.26 |
 +------------------------------------+-------------+----------------+
 | compression-supported              | RECOMMENDED | Section 5.4.32 |
 +------------------------------------+-------------+----------------+
 | document-format-supported          | RECOMMENDED | Section 5.4.22 |
 +------------------------------------+-------------+----------------+
 | finishings-supported               | OPTIONAL    | Section 5.2.6  |

Sweet & McDonald Standards Track [Page 219] RFC 8011 IPP/1.1: Model and Semantics January 2017

 +------------------------------------+-------------+----------------+
 | generated-natural-language-        | OPTIONAL    | Section 5.4.20 |
 | supported                          |             |                |
 +------------------------------------+-------------+----------------+
 | ipp-versions-supported             | RECOMMENDED | Section 5.4.14 |
 +------------------------------------+-------------+----------------+
 | media-supported                    | RECOMMENDED | Section 5.2.11 |
 +------------------------------------+-------------+----------------+
 | multiple-document-jobs-supported   | OPTIONAL    | Section 5.4.16 |
 +------------------------------------+-------------+----------------+
 | number-up-supported                | OPTIONAL    | Section 5.2.9  |
 +------------------------------------+-------------+----------------+
 | pages-per-minute-color             | OPTIONAL    | Section 5.4.37 |
 +------------------------------------+-------------+----------------+
 | pages-per-minute                   | OPTIONAL    | Section 5.4.36 |
 +------------------------------------+-------------+----------------+
 | print-quality-supported            | OPTIONAL    | Section 5.2.13 |
 +------------------------------------+-------------+----------------+
 | printer-info                       | OPTIONAL    | Section 5.4.6  |
 +------------------------------------+-------------+----------------+
 | printer-location                   | RECOMMENDED | Section 5.4.5  |
 +------------------------------------+-------------+----------------+
 | printer-make-and-model             | RECOMMENDED | Section 5.4.9  |
 +------------------------------------+-------------+----------------+
 | printer-more-info                  | OPTIONAL    | Section 5.4.7  |
 +------------------------------------+-------------+----------------+
 | printer-name                       | RECOMMENDED | Section 5.4.4  |
 +------------------------------------+-------------+----------------+
 | printer-resolution-supported       | OPTIONAL    | Section 5.2.12 |
 +------------------------------------+-------------+----------------+
 | printer-uri-supported              | RECOMMENDED | Section 5.4.1  |
 +------------------------------------+-------------+----------------+
 | sides-supported                    | RECOMMENDED | Section 5.2.8  |
 +------------------------------------+-------------+----------------+
 | uri-authentication-supported       | RECOMMENDED | Section 5.4.2  |
 +------------------------------------+-------------+----------------+
 | uri-security-supported             | RECOMMENDED | Section 5.4.3  |
 +------------------------------------+-------------+----------------+
               Table 23: Attributes in Directory Entries

Sweet & McDonald Standards Track [Page 220] RFC 8011 IPP/1.1: Model and Semantics January 2017

Acknowledgements

 The authors would like to acknowledge the following individuals for
 their contributions to the original IPP/1.1 specifications:
 Roger deBry, Tom Hastings (original RFC 2911 editor), Robert Herriot,
 Scott A. Isaacson, Kirk Ocke, Patrick Powell, and Peter Zehler

Authors' Addresses

 Michael Sweet
 Apple Inc.
 1 Infinite Loop
 MS 111-HOMC
 Cupertino, CA  95014
 United States of America
 Email: msweet@apple.com
 Ira McDonald
 High North, Inc.
 PO Box 221
 Grand Marais, MI  49839
 United States of America
 Phone: +1 906-494-2434
 Email: blueroofmusic@gmail.com

Sweet & McDonald Standards Track [Page 221]

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