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rfc:rfc2566

Network Working Group R. deBry Request for Comments: 2566 Utah Valley State College Category: Experimental T. Hastings

                                                     Xerox Corporation
                                                            R. Herriot
                                                     Xerox Corporation
                                                           S. Isaacson
                                                          Novell, Inc.
                                                             P. Powell
                                                   Astart Technologies
                                                            April 1999
        Internet Printing Protocol/1.0: Model and Semantics

Status of this Memo

 This memo defines an Experimental Protocol for the Internet
 community.  It does not specify an Internet standard of any kind.
 Discussion and suggestions for improvement are requested.
 Distribution of this memo is unlimited.

Copyright Notice

 Copyright (C) The Internet Society (1999).  All Rights Reserved.

IESG Note

 This document defines an Experimental protocol for the Internet
 community.  The IESG expects that a revised version of this protocol
 will be published as Proposed Standard protocol.  The Proposed
 Standard, when published, is expected to change from the protocol
 defined in this memo.  In particular, it is expected that the
 standards-track version of the protocol will incorporate strong
 authentication and privacy features, and that an "ipp:" URL type will
 be defined which supports those security measures.  Other changes to
 the protocol are also possible.  Implementors are warned that future
 versions of this protocol may not interoperate with the version of
 IPP defined in this document, or if they do interoperate, that some
 protocol features may not be available.
 The IESG encourages experimentation with this protocol, especially in
 combination with Transport Layer Security (TLS) [RFC 2246], to help
 determine how TLS may effectively be used as a security layer for
 IPP.

deBry, et al. Experimental [Page 1] RFC 2566 IPP/1.0: Model and Semantics April 1999

Abstract

 This document is one of a set of documents, which together describe
 all aspects of a new Internet Printing Protocol (IPP).  IPP is an
 application level protocol that can be used for distributed printing
 using Internet tools and technologies.  This document describes a
 simplified model consisting of abstract objects, their attributes,
 and their operations that is independent of encoding and transport.
 The model consists of a Printer and a Job object.  A Job optionally
 supports multiple documents.  IPP 1.0 semantics allow end-users and
 operators to query printer capabilities, submit print jobs, inquire
 about the status of print jobs and printers, and cancel print jobs.
 This document also addresses security, internationalization, and
 directory issues.
 The full set of IPP documents includes:
   Design Goals for an Internet Printing Protocol [RFC2567]
   Rationale for the Structure and Model and Protocol for the Internet
      Printing Protocol [RFC2568]
   Internet Printing Protocol/1.0: Model and Semantics (this document)
   Internet Printing Protocol/1.0: Encoding and Transport [RFC2565]
   Internet Printing Protocol/1.0: Implementer's Guide [ipp-iig]
   Mapping between LPD and IPP Protocols [RFC2569]
 The "Design Goals for an Internet Printing Protocol" document takes a
 broad look at distributed printing functionality, and it enumerates
 real-life scenarios that help to clarify the features that need to be
 included in a printing protocol for the Internet.  It identifies
 requirements for three types of users: end users, operators, and
 administrators.  It calls out a subset of end user requirements that
 are satisfied in IPP/1.0.  Operator and administrator requirements
 are out of scope for version 1.0.
 The "Rationale for the Structure and Model and Protocol for the
 Internet Printing Protocol" document describes IPP from a high level
 view, defines a roadmap for the various documents that form the suite
 of IPP specifications, and gives background and rationale for the
 IETF working group's major decisions.
 The "Internet Printing Protocol/1.0: Encoding and Transport" document
 is a formal mapping of the abstract operations and attributes defined
 in the model document onto HTTP/1.1.  It defines the encoding rules
 for a new Internet media type called "application/ipp".
 The "Internet Printing Protocol/1.0: Implementer's Guide" document
 gives insight and advice to implementers of IPP clients and IPP
 objects.  It is intended to help them understand IPP/1.0 and some of

deBry, et al. Experimental [Page 2] RFC 2566 IPP/1.0: Model and Semantics April 1999

 the considerations that may assist them in the design of their client
 and/or IPP object implementations.  For example, a typical order of
 processing requests is given, including error checking.  Motivation
 for some of the specification decisions is also included.
 The "Mapping between LPD and IPP Protocols" document gives some
 advice to implementers of gateways between IPP and LPD (Line Printer
 Daemon) implementations.

Table of Contents

1. Introduction 8 1.1 Simplified Printing Model 9 2. IPP Objects 11 2.1 Printer Object 12 2.2 Job Object 14 2.3 Object Relationships 14 2.4 Object Identity 15 3. IPP Operations 18 3.1 Common Semantics 19

3.1.1   Required Parameters                                         19
3.1.2   Operation IDs and Request IDs                               20
3.1.3   Attributes                                                  20
3.1.4   Character Set and Natural Language Operation Attributes     22
 3.1.4.1  Request Operation Attributes                              22
 3.1.4.2  Response Operation Attributes                             26
3.1.5   Operation Targets                                           28
3.1.6   Operation Status Codes and Messages                         29
3.1.7   Versions                                                    30
3.1.8   Job Creation Operations                                     32

3.2 Printer Operations 34

3.2.1   Print-Job Operation                                         34
 3.2.1.1  Print-Job Request                                         34
 3.2.1.2  Print-Job Response                                        38
3.2.2   Print-URI Operation                                         41
3.2.3   Validate-Job Operation                                      42
3.2.4   Create-Job Operation                                        42
3.2.5   Get-Printer-Attributes Operation                            43
 3.2.5.1  Get-Printer-Attributes Request                            44
 3.2.5.2  Get-Printer-Attributes Response                           46
3.2.6   Get-Jobs Operation                                          47
 3.2.6.1  Get-Jobs Request                                          47
 3.2.6.2  Get-Jobs Response                                         49

3.3 Job Operations 50

3.3.1   Send-Document Operation                                     50
 3.3.1.1  Send-Document Request                                     51
 3.3.1.2  Send-Document Response                                    53
3.3.2   Send-URI Operation                                          54

deBry, et al. Experimental [Page 3] RFC 2566 IPP/1.0: Model and Semantics April 1999

3.3.3   Cancel-Job Operation                                        54
 3.3.3.1  Cancel-Job Request                                        54
 3.3.3.2  Cancel-Job Response                                       55
3.3.4   Get-Job-Attributes Operation                                56
 3.3.4.1  Get-Job-Attributes Request                                57
 3.3.4.2  Get-Job-Attributes Response                               57

4. Object Attributes 58 4.1 Attribute Syntaxes 59

4.1.1   'text'                                                      60
 4.1.1.1  'textWithoutLanguage'                                     61
 4.1.1.2  'textWithLanguage'                                        61
4.1.2   'name'                                                      62
 4.1.2.1  'nameWithoutLanguage'                                     62
 4.1.2.2  'nameWithLanguage'                                        63
 4.1.2.3  Matching 'name' attribute values                          63
4.1.3   'keyword'                                                   64
4.1.4   'enum'                                                      65
4.1.5   'uri'                                                       65
4.1.6   'uriScheme'                                                 65
4.1.7   'charset'                                                   66
4.1.8   'naturalLanguage'                                           67
4.1.9   'mimeMediaType'                                             67
4.1.10  'octetString'                                               69
4.1.11  'boolean'                                                   69
4.1.12  'integer'                                                   69
4.1.13  'rangeOfInteger'                                            69
4.1.14  'dateTime'                                                  69
4.1.15  'resolution'                                                69
4.1.16  '1setOf  X'                                                 70

4.2 Job Template Attributes 70

4.2.1   job-priority (integer(1:100))                               74
4.2.2   job-hold-until (type3 keyword | name (MAX))                 75
4.2.3   job-sheets (type3 keyword | name(MAX))                      75
4.2.4   multiple-document-handling (type2 keyword)                  76
4.2.5   copies (integer(1:MAX))                                     77
4.2.6   finishings (1setOf type2 enum)                              78
4.2.7   page-ranges (1setOf rangeOfInteger (1:MAX))                 79
4.2.8   sides (type2 keyword)                                       80
4.2.9   number-up (integer(1:MAX))                                  80
4.2.10  orientation-requested (type2 enum)                          81
4.2.11  media (type3 keyword | name(MAX))                           82
4.2.12  printer-resolution (resolution)                             83
4.2.13  print-quality (type2 enum)                                  83

4.3 Job Description Attributes 84

4.3.1   job-uri (uri)                                               85
4.3.2   job-id (integer(1:MAX))                                     85
4.3.3   job-printer-uri (uri)                                       86
4.3.4   job-more-info (uri)                                         86

deBry, et al. Experimental [Page 4] RFC 2566 IPP/1.0: Model and Semantics April 1999

4.3.5   job-name (name(MAX))                                        86
4.3.6   job-originating-user-name (name(MAX))                       86
4.3.7   job-state (type1 enum)                                      87
4.3.8   job-state-reasons (1setOf  type2 keyword)                   90
4.3.9   job-state-message (text(MAX))                               92
4.3.10  number-of-documents (integer(0:MAX))                        93
4.3.11  output-device-assigned (name(127))                          93
4.3.12  time-at-creation (integer(0:MAX))                           93
4.3.13  time-at-processing (integer(0:MAX))                         93
4.3.14  time-at-completed (integer(0:MAX))                          94
4.3.15  number-of-intervening-jobs (integer(0:MAX))                 94
4.3.16  job-message-from-operator (text(127))                       94
4.3.17  job-k-octets (integer(0:MAX))                               94
4.3.18  job-impressions (integer(0:MAX))                            95
4.3.19  job-media-sheets (integer(0:MAX))                           95
4.3.20  job-k-octets-processed (integer(0:MAX))                     96
4.3.21  job-impressions-completed (integer(0:MAX))                  96
4.3.22  job-media-sheets-completed (integer(0:MAX))                 96
4.3.23  attributes-charset (charset)                                97
4.3.24  attributes-natural-language (naturalLanguage)               97

4.4 Printer Description Attributes 97

4.4.1   printer-uri-supported (1setOf uri)                          99
4.4.2   uri-security-supported (1setOf type2 keyword)              100
4.4.3   printer-name (name(127))                                   101
4.4.4   printer-location (text(127))                               101
4.4.5   printer-info (text(127))                                   101
4.4.6   printer-more-info (uri)                                    101
4.4.7   printer-driver-installer (uri)                             102
4.4.8   printer-make-and-model (text(127))                         102
4.4.9   printer-more-info-manufacturer (uri)                       102
4.4.10  printer-state (type1 enum)                                 102
4.4.11  printer-state-reasons (1setOf type2 keyword)               103
4.4.12  printer-state-message (text(MAX))                          106
4.4.13  operations-supported (1setOf type2 enum)                   106
4.4.14  charset-configured (charset)                               107
4.4.15  charset-supported (1setOf charset)                         107
4.4.16  natural-language-configured (naturalLanguage)              107
4.4.17  generated-natural-language-supported(1setOf naturalLanguage108
4.4.18  document-format-default (mimeMediaType)                    108
4.4.19  document-format-supported (1setOf mimeMediaType)           108
4.4.20  printer-is-accepting-jobs (boolean)                        109
4.4.21  queued-job-count (integer(0:MAX))                          109
4.4.22  printer-message-from-operator (text(127))                  109
4.4.23  color-supported (boolean)                                  109
4.4.24  reference-uri-schemes-supported (1setOf uriScheme)         109
4.4.25  pdl-override-supported (type2 keyword)                     110
4.4.26  printer-up-time (integer(1:MAX))                           110
4.4.27  printer-current-time (dateTime)                            111

deBry, et al. Experimental [Page 5] RFC 2566 IPP/1.0: Model and Semantics April 1999

4.4.28  multiple-operation-time-out (integer(1:MAX))               111
4.4.29  compression-supported (1setOf type3 keyword)               111
4.4.30  job-k-octets-supported (rangeOfInteger(0:MAX))             112
4.4.31  job-impressions-supported (rangeOfInteger(0:MAX))          112
4.4.32  job-media-sheets-supported (rangeOfInteger(0:MAX))         112

5. Conformance 112 5.1 Client Conformance Requirements 112 5.2 IPP Object Conformance Requirements 113

5.2.1   Objects                                                    113
5.2.2   Operations                                                 113
5.2.3   IPP Object Attributes                                      114
5.2.4   Extensions                                                 114
5.2.5   Attribute Syntaxes                                         115

5.3 Charset and Natural Language Requirements 115 5.4 Security Conformance Requirements 115 6. IANA Considerations (registered and private extensions) 116 6.1 Typed 'keyword' and 'enum' Extensions 116 6.2 Attribute Extensibility 119 6.3 Attribute Syntax Extensibility 119 6.4 Operation Extensibility 120 6.5 Attribute Groups 120 6.6 Status Code Extensibility 120 6.7 Registration of MIME types/sub-types for document-formats 121 6.8 Registration of charsets for use in 'charset' attribute values121 7. Internationalization Considerations 121 8. Security Considerations 125 8.1 Security Scenarios 126

8.1.1   Client and Server in the Same Security Domain              126
8.1.2   Client and Server in Different Security Domains            126
8.1.3   Print by Reference                                         127

8.2 URIs for SSL3 and non-SSL3 Access 127 8.3 The "requesting-user-name" (name(MAX)) Operation Attribute 127 8.4 Restricted Queries 129 8.5 Queries on jobs submitted using non-IPP protocols 129 8.6 IPP Security Application Profile for SSL3 130 9. References 131 10. Authors' Addresses 134 11. Formats for IPP Registration Proposals 136 11.1 Type2 keyword attribute values registration 136 11.2 Type3 keyword attribute values registration 137 11.3 Type2 enum attribute values registration 137 11.4 Type3 enum attribute values registration 137 11.5 Attribute registration 138 11.6 Attribute Syntax registration 138 11.7 Operation registration 139 11.8 Attribute Group registration 139 11.9 Status code registration 139 12.APPENDIX A: Terminology 141

deBry, et al. Experimental [Page 6] RFC 2566 IPP/1.0: Model and Semantics April 1999

12.1 Conformance Terminology 141

12.1.1  NEED NOT                                                   141

12.2 Model Terminology 141

12.2.1  Keyword                                                    141
12.2.2  Attributes                                                 141
 12.2.2.1 Attribute Name                                           141
 12.2.2.2 Attribute Group Name                                     142
 12.2.2.3 Attribute Value                                          142
 12.2.2.4 Attribute Syntax                                         142
12.2.3  Supports                                                   142
12.2.4  print-stream page                                          144
12.2.5  impression                                                 144

13.APPENDIX B: Status Codes and Suggested Status Code Messages 145 13.1 Status Codes 146

13.1.1  Informational                                              146
13.1.2  Successful Status Codes                                    146
 13.1.2.1 successful-ok (0x0000)                                   146
 13.1.2.2 successful-ok-ignored-or-substituted-attributes (0x0001) 146
 13.1.2.3 successful-ok-conflicting-attributes (0x0002)            147
13.1.3  Redirection Status Codes                                   147
13.1.4  Client Error Status Codes                                  147
 13.1.4.1 client-error-bad-request (0x0400)                        147
 13.1.4.2 client-error-forbidden (0x0401)                          147
 13.1.4.3 client-error-not-authenticated (0x0402)                  148
 13.1.4.4 client-error-not-authorized (0x0403)                     148
 13.1.4.5 client-error-not-possible (0x0404)                       148
 13.1.4.6 client-error-timeout (0x0405)                            148
 13.1.4.7 client-error-not-found (0x0406)                          149
 13.1.4.8 client-error-gone (0x0407)                               149
 13.1.4.9 client-error-request-entity-too-large (0x0408)           149
 13.1.4.10client-error-request-value-too-long (0x0409)             150
 13.1.4.11client-error-document-format-not-supported (0x040A)      150
 13.1.4.12client-error-attributes-or-values-not-supported (0x040B) 150
 13.1.4.13client-error-uri-scheme-not-supported (0x040C)           151
 13.1.4.14client-error-charset-not-supported (0x040D)              151
 13.1.4.15client-error-conflicting-attributes (0x040E)             151
13.1.5  Server Error Status Codes                                  151
 13.1.5.1 server-error-internal-error (0x0500)                     151
 13.1.5.2 server-error-operation-not-supported (0x0501)            152
 13.1.5.3 server-error-service-unavailable (0x0502)                152
 13.1.5.4 server-error-version-not-supported (0x0503)              152
 13.1.5.5 server-error-device-error (0x0504)                       152
 13.1.5.6 server-error-temporary-error (0x0505)                    153
 13.1.5.7 server-error-not-accepting-jobs (0x0506)                 153
 13.1.5.8 server-error-busy (0x0507)                               153
 13.1.5.9 server-error-job-canceled (0x0508)                       153

13.2 Status Codes for IPP Operations 153 14.APPENDIX C: "media" keyword values 155

deBry, et al. Experimental [Page 7] RFC 2566 IPP/1.0: Model and Semantics April 1999

15.APPENDIX D: Processing IPP Attributes 160 15.1 Fidelity 160 15.2 Page Description Language (PDL) Override 161 15.3 Using Job Template Attributes During Document Processing. 163 16.APPENDIX E: Generic Directory Schema 166 17.APPENDIX F: Change History for the Model and Semantics document 168 18.FULL COPYRIGHT STATEMENT 173

1. Introduction

 The Internet Printing Protocol (IPP) is an application level protocol
 that can be used for distributed printing using Internet tools and
 technologies.  IPP version 1.0 (IPP/1.0) focuses only on end user
 functionality.  This document is just one of a suite of documents
 that fully define IPP.  The full set of IPP documents includes:
   Design Goals for an Internet Printing Protocol [RFC2567]
   Rationale for the Structure and Model and Protocol for the Internet
      Printing Protocol [RFC2568]
   Internet Printing Protocol/1.0: Model and Semantics (this document)
   Internet Printing Protocol/1.0: Encoding and Transport [RFC2565]
   Internet Printing Protocol/1.0: Implementer's Guide [ipp-iig]
   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.
 This document is laid out as follows:
  1. The rest of Section 1 is an introduction to the IPP simplified

model for distributed printing.

  1. Section 2 introduces the object types covered in the model with

their basic behaviors, attributes, and interactions.

  1. Section 3 defines the operations included in IPP/1.0. IPP

operations are synchronous, therefore, for each operation, there

     is a both request and a response.
   - Section 4 defines the attributes (and their syntaxes) that are
     used in the model.
   - Sections 5 - 6 summarizes the implementation conformance
     requirements for objects that support the protocol and IANA
     considerations, respectively.
   - Sections 7 - 11 cover the Internationalization and Security
     considerations as well as References, Author contact information,
     and Formats for Registration Proposals.
   - Sections 12 - 14 are appendices that cover Terminology, Status
     Codes and Messages, and "media" keyword values.

deBry, et al. Experimental [Page 8] RFC 2566 IPP/1.0: Model and Semantics April 1999

           Note: This document uses terms such as "attributes",
           "keywords", and "support".  These terms have special
           meaning and are defined in the model terminology section
           12.2.  Capitalized terms, such as MUST, MUST NOT, REQUIRED,
           SHOULD, SHOULD NOT, MAY, NEED NOT, and OPTIONAL, have
           special meaning relating to conformance.  These terms are
           defined in section 12.1 on conformance terminology, most of
           which is taken from RFC 2119 [RFC2119].
  1. Section 15 is an appendix that helps to clarify the effects of

interactions between related attributes and their values.

  1. Section 16 is an appendix that enumerates the subset of Printer

attributes that form a generic directory schema. These

     attributes are useful when registering a Printer so that a
     client can find the Printer not just by name, but by filtered
     searches as well.
   - Section 17 is an appendix that provides a Change History
     summarizing the clarification and changes that might affect an
     implementation since the June 30, 1998 draft.

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 model and semantics document
 describes a simple, abstract model for IPP even though the underlying
 configurations may 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 model document does not include features, interfaces, and
 relationships that are beyond the scope of the first version of IPP
 (IPP/1.0).  IPP/1.0 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 version 1.0
 (IPP/1.0) focuses only on end user functionality.
 The IPP/1.0 model encapsulates the important components of
 distributed printing into two object types:
  1. Printer (Section 2.1)
  2. Job (Section 2.2)

deBry, et al. Experimental [Page 9] RFC 2566 IPP/1.0: Model and Semantics April 1999

 Each object type has an associated set of operations (see section 3)
 and attributes (see section 4).
 It is important, however, to understand that in real system
 implementations (which lie underneath the abstracted IPP/1.0 model),
 there are other components of a print service which are not
 explicitly defined in the IPP/1.0 model. The following figure
 illustrates where IPP/1.0 fits with respect to these other
 components.
                              +--------------+
                              |  Application |
                    o         +. . . . . . . |
                   \|/        |   Spooler    |
                   / \        +. . . . . . . |   +---------+
                 End-User     | Print 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)|
                     +-----------------+
 An IPP Printer object 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. Printer objects are optionally registered as entries in a
 directory where end users find and select them based on some sort of
 filtered and context based searching mechanism (see section 16).  The
 directory is used to store relatively static information about the
 Printer, allowing end users to search for and find Printers that

deBry, et al. Experimental [Page 10] RFC 2566 IPP/1.0: Model and Semantics April 1999

 match their search criteria, for example: name, context, printer
 capabilities, etc.  The more dynamic information, such as state,
 currently loaded and ready media, number of jobs at the Printer,
 errors, warnings, and so forth, is directly associated with the
 Printer object itself rather than with the entry in the directory
 which only represents the Printer object.
 IPP clients implement the IPP protocol on the client side and give
 end users (or programs running on behalf of end users) the ability to
 query Printer objects 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.
 The Printer objects may be embedded in an output device or may be
 implemented on a host on the network that communicates with an output
 device.
 When a job is submitted to the Printer object and the Printer object
 validates the attributes in the submission request, the Printer
 object creates a new Job object.  The end user then interacts with
 this new Job object to query its status and monitor the progress of
 the job.  End users may also cancel the print job by using the Job
 object's Cancel-Job operation.  The notification service is out of
 scope for IPP/1.0, but using such a notification service, the end
 user is able to register for and receive Printer specific and Job
 specific events.  An end user can query the status of Printer objects
 and can follow the progress of Job objects by polling using the Get-
 Printer-Attributes, Get-Jobs, and Get-Job-Attributes operations.

2. IPP Objects

 The IPP/1.0 model introduces objects of type 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 may 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:

deBry, et al. Experimental [Page 11] RFC 2566 IPP/1.0: Model and Semantics April 1999

  1. "REQUIRED": each object MUST support the attribute.
  2. "OPTIONAL": each object MAY support the attribute.
 There is no such similar labeling of attribute values.  However, if
 an implementation supports an attribute, it MUST support at least one
 of the possible values for that attribute.

2.1 Printer Object

 The major component of the IPP/1.0 model is the Printer object.  A
 Printer object implements the server-side of the IPP/1.0 protocol.
 Using the protocol, end users may query the attributes of the Printer
 object and submit print jobs to the Printer object.  The actual
 implementation components behind the Printer abstraction may 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 3 describes
 each of the Printer operations in detail.
 The capabilities and state of a Printer object are described by its
 attributes.  Printer attributes are divided into two groups:
  1. "job-template" attributes: These attributes describe supported

job processing capabilities and defaults for the Printer object.

     (See section 4.2)
   - "printer-description" attributes: These attributes describe the
     Printer object's identification, state, location, references to
     other sources of information about the Printer object, etc. (see
     section 4.4)
 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 may or may not be capable of
        spooling jobs
      3b) The associated output devices may or may not support IPP

deBry, et al. Experimental [Page 12] RFC 2566 IPP/1.0: Model and Semantics April 1999

 The following figures show some examples of how Printer objects can
 be realized on top of various distributed printing configurations.
 The embedded case below represents configurations 1 and 2. The hosted
 and fan-out figures below represent configurations 3a and 3b.
 Legend:
 ##### indicates a Printer object which is
       either embedded in an output device or is
       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 |
                                          |               |
                                          +---------------+

deBry, et al. Experimental [Page 13] RFC 2566 IPP/1.0: Model and Semantics April 1999

2.2 Job Object

 A Job object is used to model a print job.  A Job object contains
 documents.  The information required to create a Job object is sent
 in a create request from the end user via an IPP Client to the
 Printer object.  The Printer object validates the create request, and
 if the Printer object accepts the request, the Printer object creates
 the new Job object.  Section 3 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:
  1. "job-template" attributes: These attributes can be supplied by

the client or end user and include job processing instructions

     which are intended to override any Printer object defaults and/or
     instructions embedded within the document data. (See section 4.2)
   - "job-description" attributes: These attributes describe the Job
     object's identification, state, size, etc. The client supplies
     some of these attributes, and the Printer object generates others.
     (See section 4.3)
 An implementation MUST support at least one document per Job object.
 An implementation MAY support multiple documents per Job object.  A
 document is either:
  1. a stream of document data in a format supported by the Printer

object (typically a Page Description Language - PDL), or

  1. a reference to such a stream of document data
 In IPP/1.0, a document is not modeled as an IPP object, therefore it
 has no object identifier or associated attributes.  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.

2.3 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 which "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 object contains
 zero or more Job objects.

deBry, et al. Experimental [Page 14] RFC 2566 IPP/1.0: Model and Semantics April 1999

 A Job object is contained by exactly one Printer object, however the
 identical document data associated with a Job object could be sent to
 either the same or a different Printer object.  In this case, a
 second Job object would be created which would be almost identical to
 the first Job object, however it would have new (different) Job
 object identifiers (see section 2.4).
 A Job object is either 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 Job objects.  If the
 contained document is just a reference to a stream of document data,
 other documents (in the same or different Job object(s)) may contain
 the same reference.

2.4 Object Identity

 All Printer and Job objects are identified by a Uniform Resource
 Identifier (URI) [RFC2396] so that they can be persistently and
 unambiguously referenced.  The notion of a URI is a useful concept,
 however, until the notion of URI is more stable (i.e., defined more
 completely and deployed more widely), it is expected that the URIs
 used for IPP objects will actually be URLs [RFC2396].  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 Printer objects to either support or not
 support authentication and/or message privacy using SSL3 [SSL] (the
 mechanism for security configuration is outside the scope of
 IPP/1.0).  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 8 provides a full
 description of all security considerations and configurations.
 If a Printer object 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 object where each URI represents
 one of the communication channels to the Printer object. To support
 this flexibility, the IPP Printer object type defines a multi-valued
 identification attribute called the "printer-uri-supported"
 attribute.  It MUST contain at least one URI.  It MAY contain more
 than one URI.  That is, every Printer object will have at least one

deBry, et al. Experimental [Page 15] RFC 2566 IPP/1.0: Model and Semantics April 1999

 URI that identifies at least one communication channel to the Printer
 object, but it may have more than one URI where each URI identifies a
 different communication channel to the Printer object.  The
 "printer-uri-supported" attribute has a companion attribute, the
 "uri-security-supported" attribute, that has the same cardinality as
 "printer-uri-supported".  The purpose of the "uri-security-supported"
 attribute is to indicate the security mechanisms (if any) used for
 each URI listed in "printer-uri-supported".  These two attributes are
 fully described in sections 4.4.1 and 4.4.2.
 When a job is submitted to the Printer object via a create request,
 the client supplies only a single Printer object URI.  The client
 supplied Printer object URI MUST be one of the values in the
 "printer-uri-supported" Printer attribute.
 Note:  IPP/1.0 does not specify how the client obtains the client
 supplied URI, but it is RECOMMENDED that a Printer object be
 registered as an entry in a directory service.  End-users and
 programs can then interrogate the directory searching for Printers.
 Section 16 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 object.  The entry in the directory that
 represents the IPP Printer object includes the possibly many URIs for
 that Printer object as values in one its attributes.
 When a client submits a create request to the Printer object, the
 Printer object validates the request and creates a new Job object.
 The Printer object assigns the new Job object a URI which is stored
 in the "job-uri" Job attribute.  This URI is then used by clients as
 the target for subsequent Job operations.  The Printer object
 generates a Job URI based on its configured security policy and the
 URI used by the client in the create request.
 For example, consider a Printer object that supports both a
 communication channel secured by the use of SSL3 (using HTTP over
 SSL3 with an "https" schemed URI) and another open communication
 channel that is not secured with SSL3 (using a simple "http" schemed
 URI).  If a client were to submit a job using the secure URI, the
 Printer object would assign the new Job object a secure URI as well.
 If a client were to submit a job using the open-channel URI, the
 Printer would assign the new Job object an open-channel URI.
 In addition, the Printer object also populates the Job object's
 "job-printer-uri" attribute.  This is a reference back to the Printer
 object that created the Job object.  If a client only has access to a
 Job object's "job-uri" identifier, the client can query the Job's
 "job-printer-uri" attribute in order to determine which Printer
 object created the Job object.  If the Printer object supports more

deBry, et al. Experimental [Page 16] RFC 2566 IPP/1.0: Model and Semantics April 1999

 than one URI, the Printer object 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.
 Allowing Job objects to have URIs allows for flexibility and
 scalability.  For example, in some implementations, the Printer
 object might create Jobs that are processed in the same local
 environment as the Printer object itself.  In this case, the Job URI
 might just be a composition of the Printer's URI and some unique
 component for the Job object, such as the unique 32-bit positive
 integer mentioned later in this paragraph.  In other implementations,
 the Printer object might be a central clearing-house for validating
 all Job object creation requests, but the Job object itself might be
 created in some environment that is remote from the Printer object.
 In this case, the Job object's URI may have no physical-location
 relationship at all to the Printer object's URI.  Again, the fact
 that Job objects have URIs allows for flexibility and scalability,
 however, many existing printing systems have local models or
 interface constraints that force print jobs to be identified using
 only a 32-bit positive integer rather than an independent URI.  This
 numeric Job ID is only unique within the context of the Printer
 object to which the create request was originally submitted.
 Therefore, in order to allow both types of client access to IPP Job
 objects (either by Job URI or by numeric Job ID), when the Printer
 object successfully processes a create request and creates a new Job
 object, the Printer object MUST generate both a Job URI and a Job ID.
 The Job ID (stored in the "job-id" attribute) only has meaning in the
 context of the Printer object to which the create request was
 originally submitted. This requirement to support both Job URIs and
 Job IDs allows all types of clients to access Printer objects and Job
 objects no matter the local constraints imposed on the client
 implementation.
 In addition to identifiers, Printer objects and Job objects have
 names ("printer-name" and "job-name").  An object name NEED NOT be
 unique across all instances of all objects. A Printer object's name
 is chosen and set by an administrator through some mechanism outside
 the scope of IPP/1.0.  A Job object's name is optionally chosen and
 supplied by the IPP client submitting the job.  If the client does
 not supply a Job object name, the Printer object generates a name for
 the new Job object.  In all cases, the name only has local meaning.
 To summarize:
  1. Each Printer object is identified with one or more URIs. The

Printer's "printer-uri-supported" attribute contains the URI(s).

deBry, et al. Experimental [Page 17] RFC 2566 IPP/1.0: Model and Semantics April 1999

  1. The Printer object's "uri-security-supported" attribute

identifies the communication channel security protocols that may

     or may not have been configured for the various Printer object
     URIs (e.g., 'ssl3' or 'none').
   - Each Job object is identified with a Job URI.  The Job's "job-uri"
     attribute contains the URI.
   - Each Job object is also identified with Job ID 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
     object  which created the Job object.
   - Each Job object has a "job-printer-uri" attribute which contains
     the URI of the Printer object that was used to create the Job
     object.  This attribute is used to determine the Printer object
     that created a Job object when given only the URI for the Job
     object.  This linkage is necessary to determine the languages,
     charsets, and operations which are supported on that Job (the
     basis for such support comes from the creating Printer object).
   - Each Printer object has a name (which is not necessarily unique).
     The administrator chooses and sets this name through some
     mechanism outside the scope of IPP/1.0 itself.  The Printer
     object's "printer-name" attribute contains the name.
   - Each Job object has a name (which is not necessarily unique).  The
     client optionally supplies this name in the create request.  If
     the client does not supply this name, the Printer object generates
     a name for the Job object. The Job object's "job-name" attribute
     contains the name.

3. IPP Operations

 IPP objects support operations.  An operation consists of a request
 and a response.  When a client communicates with an IPP object, the
 client issues an operation request to the URI for that object.
 Operation requests and responses have parameters that identify the
 operation.  Operations also have attributes that affect the run-time
 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 object attributes or Job object 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.

deBry, et al. Experimental [Page 18] RFC 2566 IPP/1.0: Model and Semantics April 1999

 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 IPP/1.0 Printer operations are:
   Print-Job (section 3.2.1)
   Print-URI (section 3.2.2)
   Validate-Job (section 3.2.3)
   Create-Job (section 3.2.4)
   Get-Printer-Attributes (section 3.2.5)
   Get-Jobs (section 3.2.6)
 The Job operations are:
   Send-Document (section 3.3.1)
   Send-URI (section 3.3.2)
   Cancel-Job (section 3.3.3)
   Get-Job-Attributes (section 3.3.4)
 The Send-Document and Send-URI Job operations are used to add a new
 document to an existing multi-document Job object created using the
 Create-Job operation.

3.1 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.

3.1.1 Required Parameters

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

and

  1. the attributes that are REQUIRED for that type of response.

deBry, et al. Experimental [Page 19] RFC 2566 IPP/1.0: Model and Semantics April 1999

 The encoding and transport document [RFC2565] 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.

3.1.2 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 4.4.13).  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 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 mappings, the operation responses can
 come back in any order.  In these cases, the "request-id" would be
 essential.

3.1.3 Attributes

 Operation requests and responses are both composed of groups of
 attributes and/or document data.  The attributes groups are:
  1. Operation Attributes: These attributes are passed in the

operation and affect the IPP object's behavior while processing

     the operation request and may 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 operation attributes are REQUIRED and which are OPTIONAL

deBry, et al. Experimental [Page 20] RFC 2566 IPP/1.0: Model and Semantics April 1999

     for an IPP object to support and which attributes a client MUST
     supply in a request and an IPP object MUST supply in a response.
   - Job Template Attributes: These attributes affect the processing
     of a job.  A client OPTIONALLY supplies Job Template Attributes
     in a create 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 create 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 15
     for a full description of "ipp-attribute-fidelity" and its
     relationship to other attributes).
   - Job Object Attributes: These attributes are returned in response
     to a query operation directed at a Job object.
   - Printer Object Attributes: These attributes are returned in
     response to a query operation directed at a Printer object.
   - Unsupported Attributes: In a create request, the client supplies
     a set of Operation and Job Template attributes.  If any of these
     attributes or their values is unsupported by the Printer object,
     the Printer object returns the set of unsupported attributes in
     the response.  Section 15 gives a full description of how Job
     Template attributes supplied by the client in a create 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.
 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 may be in any order, unless specified otherwise.
 Each attribute specification includes the attribute's name followed
 by the name of its attribute syntax(es) in parenthesizes.  In
 addition, each 'integer' attribute is followed by the allowed range
 in parentheses, (m:n), for values of that attribute.  Each 'text' or
 'name' attribute is 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
 attributes syntaxes in section 4.1.

deBry, et al. Experimental [Page 21] RFC 2566 IPP/1.0: Model and Semantics April 1999

 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 that support supplying the
 document data within an operation request are Print-Job and Send-
 Document.  There are no operation responses that include document
 data.
 Note: Some operations are REQUIRED for IPP objects to support; the
 others are OPTIONAL (see section 5.2.2).  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 Printer and
 Job 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
 returns the 'server-error-operation-not-supported' status code (see
 section 13.1.5.2).  An IPP object is non-conformant if it does not
 support a REQUIRED operation.

3.1.4 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 4.1).  The following sections describe two
 special Operation Attributes called "attributes-charset" and
 "attributes-natural-language".  These attributes are always part of
 the Operation Attributes group.  For most attribute groups, the order
 of the attributes within the group is not important.  However, for
 these two attributes within the Operation Attributes group, the order
 is critical.  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.  In other words,
 these attributes MUST be supplied in every IPP request and response,
 they MUST come first in the group, and MUST come in the specified
 order.  For job creation operations, the IPP Printer implementation
 saves these two attributes with the new Job object as Job Description
 attributes.  For the sake of brevity in this document, these
 operation attribute descriptions are not repeated with every
 operation request and response, but have a reference back to this
 section instead.

3.1.4.1 Request Operation Attributes

 The client MUST supply and the Printer object MUST support the
 following REQUIRED operation attributes in every IPP/1.0 operation
 request:

deBry, et al. Experimental [Page 22] RFC 2566 IPP/1.0: Model and Semantics April 1999

   "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 4.1.1 and 4.1.2 for the specification of
      the 'text' and 'name' attribute syntaxes.
      All clients and IPP objects MUST support the 'utf-8' charset
      [RFC2279] and MAY support additional charsets provided that they
      are registered with IANA [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 object MUST indicate the
      charset(s) supported as the values of the "charset-supported"
      Printer attribute (see Section 4.4.15), so that the client can
      query to determine which charset(s) are supported.
      Note to client implementers: Since IPP objects are only required
      to support the 'utf-8' charset, in order to maximize
      interoperability with multiple IPP object implementations, a
      client may want to 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 or ISO-
      8859-1.  Then the client will have to filter out (or charset
      convert) 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 may want to use that charset in order
      to avoid charset conversion or data loss.
      See the 'charset' attribute syntax description in Section 4.1.7
      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 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.

deBry, et al. Experimental [Page 23] RFC 2566 IPP/1.0: Model and Semantics April 1999

      There are no REQUIRED natural languages required for the Printer
      object to support.  However, the Printer object's "generated-
      natural-language-supported" attribute identifies the natural
      languages supported by the Printer object and any contained Job
      objects for all text strings generated by the IPP object.  A
      client MAY query this attribute to determine which natural
      language(s) are 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 3.1.6), 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 4.4.16).
      For other 'text' and 'name' attributes supplied by the client,
      authentication system, operator, system 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 object'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
      4.1.1.2 and 4.1.2.2) 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 object's "generated-natural-language-
      supported" attribute.  That attribute, "generated-natural-
      language-supported", only applies to generated messages,

deBry, et al. Experimental [Page 24] RFC 2566 IPP/1.0: Model and Semantics April 1999

      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 4.1.1 and 4.1.2) 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:
  1. 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 4.1.1.1
             textWithoutLanguage and 4.1.2.1 nameWithoutLanguage).
  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 4.1.1.2
             textWithLanguage and 4.1.2.2 nameWithLanguage).
      For example, the "job-name" attribute MAY be supplied by the
      client in a create 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 object's "job-name" attribute.  Whenever any
      client queries the Job object'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.
      See the 'naturalLanguage' attribute syntax description in
      section 4.1.8 for the syntax and semantic interpretation of the
      values of this attribute and for example values.

deBry, et al. Experimental [Page 25] RFC 2566 IPP/1.0: Model and Semantics April 1999

 Clients SHOULD NOT supply 'text' or 'name' attributes that use an
 illegal combination of natural language and charset.  For example,
 suppose a Printer object 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
 object 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 object handles this
 apparent incompatibility differently depending on the context in
 which it occurs:
  1. In a create 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 object or its correct
     operation.  Therefore, the Printer object simply accepts the
     client supplied value, stores it with the Job object, 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 object responds (as described in section 3.1.4.2) using
     the Printer's configured natural language rather than the natural
     language requested by the client.
 In either case, the Printer object 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.

3.1.4.2 Response Operation Attributes

 The Printer object MUST supply and the client MUST support the
 following REQUIRED operation attributes in every IPP/1.0 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

deBry, et al. Experimental [Page 26] RFC 2566 IPP/1.0: Model and Semantics April 1999

      (i.e., the charset requested is not supported), the request
      would have been rejected.  See "attributes-charset" described in
      Section 3.1.4.1 above.
      If the Printer object supports more than just the 'utf-8'
      charset, the Printer object MUST be able to code convert 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
      MAY occur during the charset conversion depending on the
      charsets involved.  For example, the Printer object may 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 '?', decimal code equivalent, or to the
      absence of a character, depending on implementation.
      Note: Whether an implementation that supports more than one
      charset stores the data in the charset supplied by the client or
      code converts 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.
   "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 NEED NOT return the same
      value as that supplied by the client in the request.  The IPP
      object MAY return the natural language of the Job object or the
      Printer's configured natural language as identified by the
      Printer object'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 4.1.1.2 and 4.1.2.2) 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.

deBry, et al. Experimental [Page 27] RFC 2566 IPP/1.0: Model and Semantics April 1999

3.1.5 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
 object'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 (uri)"
 operation attribute.
 For Job operations, the operation is directed at either:
  1. The Job object itself using the Job object's URI. In this case,

the client identifies the target object by supplying the correct

     URI in the "job-uri (uri)" operation attribute.
   - The Printer object that created the Job object using both the
     Printer objects URI and the Job object's 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
     object's URI in the "printer-uri (uri)" operation attribute and
     the Job object's Job ID in the "job-id (integer(1:MAX))"
     operation attribute.
 If the operation is directed at the Job object directly using the Job
 object's URI, the client MUST NOT include the redundant "job-id"
 operation attribute.
 The operation target attributes are REQUIRED operation attributes
 that MUST be included in every operation request.  Like the charset
 and natural language attributes (see section 3.1.4), 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 attribute group, however the specific ordering
 rules are:
  1. 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.
   - 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.

deBry, et al. Experimental [Page 28] RFC 2566 IPP/1.0: Model and Semantics April 1999

 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 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.
 Note: The IPP encoding and transport document [RFC2565] shows a
 mapping of IPP onto HTTP/1.1 and defines a new default port number
 for using IPP over HTTP/1.1.

3.1.6 Operation Status Codes and Messages

 Every operation response includes a REQUIRED "status-code" parameter
 and an OPTIONAL "status-message" operation attribute.  The "status-
 code" provides information on the processing of a request.  A
 "status-message" attribute provides a short textual description of
 the status of the operation.  The status code is intended for use by
 automata, and the status message is intended for the human end user.
 If a response does include a "status-message" attribute, an IPP
 client NEED NOT examine or display the message, however it SHOULD do
 so in some implementation specific manner.
 The "status-code" value is a numeric value that has semantic meaning.
 The "status-code" syntax is similar to a "type2 enum" (see section
 4.1 on "Attribute Syntaxes") except that values can range only from
 0x0000 to 0x7FFF.  Section 13 describes the status codes, assigns the
 numeric values, and suggests a corresponding status message for each
 status code.  The "status-message" attribute's syntax is "text(255)".
 A client implementation of IPP SHOULD convert status code values into
 any localized message that has semantic meaning to the end user.

deBry, et al. Experimental [Page 29] RFC 2566 IPP/1.0: Model and Semantics April 1999

 If the Printer object supports the "status-message" operation
 attribute, the Printer object MUST be able to generate this message
 in any of the natural languages identified by the Printer object's
 "generated-natural-language-supported" attribute (see the
 "attributes-natural-language" operation attribute specified in
 section 3.1.4.1).  As described in section 3.1.4.1 for any returned '
 text' attribute, if there is a choice for generating this message,
 the Printer object uses the natural language indicated by the value
 of the "attributes-natural-language" in the client request if
 supported, otherwise the Printer object uses the value in the Printer
 object's own "natural-language-configured" attribute.  If the Printer
 object supports the "status-message" operation attribute, it SHOULD
 use the REQUIRED 'utf-8' charset to return a status message for the
 following error status codes (see section 13): '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.

3.1.7 Versions

 Each operation request and response carries with it a "version-
 number" parameter.  Each value of the "version-number" 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.  If the IPP object does not support that version, the
 object responds with a status code of 'server-error-version-not-
 supported' along with the closest version number that is supported
 (see section 13.1.5.4).
 There is no version negotiation per se.  However, if after receiving
 a 'server-error-version-not-supported' status code from an IPP
 object, there is nothing that prevents a client from trying again
 with a different version number. In order to conform to IPP/1.0, an
 implementation MUST support at least version '1.0'.
 There is only one notion of "version number" that covers both IPP
 Model and IPP Protocol changes. Thus the version number MUST change
 when introducing a new version of the Model and Semantics document
 [RFC2566] or a new version of the Encoding and Transport document
 [RFC2565].
 Changes to the major version number indicate structural or syntactic
 changes that make it impossible for older version of IPP clients and
 Printer objects to correctly parse and process the new or changed
 attributes, operations and responses.  If the major version number

deBry, et al. Experimental [Page 30] RFC 2566 IPP/1.0: Model and Semantics April 1999

 changes, the minor version numbers is set to zero.  As an example,
 adding the "ipp-attribute-fidelity" attribute (if it had not been
 part of version '1.0'), would have required a change to the major
 version number.  Items that might affect the changing of the major
 version number include any changes to the Model and Semantics
 document [RFC2566] or the Encoding and Transport [RFC2565] itself,
 such as:
  1. reordering of ordered attributes or attribute sets
  2. changes to the syntax of existing attributes
  3. changing Operation or Job Template attributes from OPTIONAL to

REQUIRED and vice versa

  1. adding REQUIRED (for an IPP object to support) operation

attributes

  1. adding REQUIRED (for an IPP object to support) operation

attribute groups

  1. adding values to existing operation attributes
  2. adding REQUIRED operations
 Changes to the minor version number indicate the addition of new
 features, attributes and attribute values that may not be understood
 by all IPP objects, but which 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 [RFC2565] (except adding attribute
 syntaxes).  Examples of such changes are:
  1. grouping all extensions not included in a previous version into

a new version

  1. adding new attribute values
  2. adding new object attributes
  3. adding OPTIONAL (for an IPP object to support) operation

attributes (i.e., those attributes that an IPP object can ignore

     without confusing clients)
   - adding OPTIONAL (for an IPP object to support) operation
     attribute groups (i.e., those attributes that an IPP object can
     ignore without confusing clients)
   - adding new attribute syntaxes
   - adding OPTIONAL operations
   - changing Job Description attributes or Printer Description
     attributes from OPTIONAL to REQUIRED or vice versa.
 The encoding of the "operation-id", the "version-number", the
 "status-code", and the "request-id" 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 "operation-id", the "version-number", and the
 "request-id").  In addition, any protocol elements (attributes, error

deBry, et al. Experimental [Page 31] RFC 2566 IPP/1.0: Model and Semantics April 1999

 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.
 Implementations that support a certain major version NEED NOT support
 ALL previous versions.  As each new major version is defined (through
 the release of a new specification), that major version will specify
 which previous major versions MUST be supported in compliant
 implementations.

3.1.8 Job Creation Operations

 In order to "submit a print job" and create a new Job object, a
 client issues a create request.  A create request is any one of
 following three operation requests:
  1. The Print-Job Request: A client that wants to submit a print job

with only a single document uses the Print-Job operation. The

     operation allows for the client to "push" the document data to
     the Printer object by including the document data in the request
     itself.
  1. The Print-URI Request: A client that wants to submit a print job

with only a single document (where the Printer object "pulls" the

     document data instead of the client "pushing" the data to the
     Printer object) 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).
  1. The Create-Job Request: A client that wants to submit a print job

with multiple 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 create Job object).  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 object includes a "last-document" operation attribute
     set to 'true' indicating that this is the last request.
 Throughout this model specification, the term "create 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, for
 performance reasons, the client SHOULD use the Print-Job operation

deBry, et al. Experimental [Page 32] RFC 2566 IPP/1.0: Model and Semantics April 1999

 for all single document jobs.  Also, Print-Job is a REQUIRED
 operation (all implementations MUST support it) whereas Create-Job is
 an OPTIONAL operation, hence some implementations might not support
 it.
 Job submission time is the point in time when a client issues a
 create request.  The initial state of every Job object is the '
 pending' or 'pending-held' state.  Later, the Printer object begins
 processing the print job.  At this point in time, the Job object's
 state moves to 'processing'.  This is known as job processing time.
 There are validation checks that must be done at job submission time
 and others that must be performed at 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 object MUST validate whether or
 not the supplied attributes, attribute syntaxes, and values are
 supported by matching them with the Printer object's corresponding
 "xxx-supported" attributes.  See section 3.2.1.2 for details.  [ipp-
 iig] presents suggested steps for an IPP object to either accept or
 reject any request and additional steps for processing create
 requests.
 At job submission time the Printer object NEED NOT perform the
 validation checks reserved for job processing time such as:
   1. Validating 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 object might discover any of the following conditions that
 were not detectable at job submission time:
  1. runtime errors in the document data,
  2. nested document data that is in an unsupported format,

deBry, et al. Experimental [Page 33] RFC 2566 IPP/1.0: Model and Semantics April 1999

  1. the URI reference is no longer valid (i.e., the server hosting

the document might be down), or

  1. any other job processing error
 At job processing time, since the Printer object has already
 responded with a successful status code in the response to the create
 request, if the Printer object detects an error, the Printer object
 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-state", "job-state-reasons", 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 outside the scope of
 IPP/1.0.

3.2 Printer Operations

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

3.2.1 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 Section 15 for the suggested steps for
 processing create operations and their Operation and Job Template
 attributes.

3.2.1.1 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 3.1.4.1.  The Printer object
      MUST copy these values to the corresponding Job Description
      attributes described in sections 4.3.23 and 4.3.24.
   Target:
      The "printer-uri" (uri) operation attribute which is the target
      for this operation as described in section 3.1.5.

deBry, et al. Experimental [Page 34] RFC 2566 IPP/1.0: Model and Semantics April 1999

   Requesting User Name:
      The "requesting-user-name" (name(MAX)) attribute SHOULD be
      supplied by the client as described in section 8.3.
   "job-name" (name(MAX)):
      The client OPTIONALLY supplies this attribute.  The Printer
      object 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 object.  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 object (see
      Section 4.3.5).
   "ipp-attribute-fidelity" (boolean):
      The client OPTIONALLY supplies this attribute.  The Printer
      object MUST support this attribute.  The value 'true' indicates
      that total fidelity to client supplied Job Template attributes
      and values is required, else the Printer object MUST reject the
      Print-Job request.  The value 'false' indicates that a
      reasonable attempt to print the Job object is acceptable and the
      Printer object MUST accept the Print-job request. If not
      supplied, the Printer object assumes the value is 'false'.  All
      Printer objects MUST support both types of job processing.  See
      section 15 for a full description of "ipp-attribute-fidelity"
      and its relationship to other attributes, especially the Printer
      object's "pdl-override-supported" attribute.
   "document-name" (name(MAX)):
      The client OPTIONALLY supplies this attribute.  The Printer
      object 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: 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.  IPP/1.0 does not
      support the concept of document level attributes.

deBry, et al. Experimental [Page 35] RFC 2566 IPP/1.0: Model and Semantics April 1999

   "document-format" (mimeMediaType) :
      The client OPTIONALLY supplies this attribute.  The Printer
      object MUST support this attribute.  The value of this attribute
      identifies the format of the supplied document data.  If the
      client does not supply this attribute, the Printer object
      assumes that the document data is in the format defined by the
      Printer object's "document-format-default" attribute.  If the
      client supplies this attribute, but the value is not supported
      by the Printer object, i.e., the value is not one of the values
      of the Printer object's "document-format-supported" attribute,
      the Printer object MUST reject the request and return the '
      client-error-document-format-not-supported' status code.
   "document-natural-language" (naturalLanguage):
      The client OPTIONALLY supplies this attribute.  The Printer
      object OPTIONALLY supports this attribute. This attribute
      specifies the natural language of the document for those
      document-formats that require a specification of the natural
      language in order to image the document unambiguously. There are
      no particular values required for the Printer object to support.
   "compression" (type3 keyword)
      The client OPTIONALLY supplies this attribute.  The Printer
      object OPTIONALLY supports this attribute and the "compression-
      supported" attribute (see section 4.4.29).  The client supplied
      "compression" operation attribute identifies the compression
      algorithm used on the document data.  If the client omits this
      attribute, the Printer object MUST assume that the data is not
      compressed.  If the client supplies the attribute and the
      Printer object supports the attribute, the Printer object uses
      the corresponding decompression algorithm on the document data.
      If the client supplies this attribute, but the value is not
      supported by the Printer object, i.e., the value is not one of
      the values of the Printer object's "compression-supported"
      attribute, the Printer object MUST copy the attribute and its
      value to the Unsupported Attributes response group, reject the
      request, and return the 'client-error-attributes-or-values-not-
      supported' status code.
   "job-k-octets" (integer(0:MAX))
      The client OPTIONALLY supplies this attribute.  The Printer
      object OPTIONALLY supports this attribute and the "job-k-
      octets-supported" attribute (see section 4.4.30).  The client
      supplied "job-k-octets" operation attribute identifies the total
      size of the document(s) in K octets being submitted (see section
      4.3.17 for the complete semantics).  If the client supplies the

deBry, et al. Experimental [Page 36] RFC 2566 IPP/1.0: Model and Semantics April 1999

      attribute and the Printer object supports the attribute, the
      value of the attribute is used to populate the Job object's
      "job-k-octets" Job Description attribute.
      Note: For this attribute and the following two attributes
      ("job-impressions", and "job-media-sheets"), if the client
      supplies the attribute, but the Printer object does not support
      the attribute, the Printer object 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 object's "xxx-supported" attribute, the
      Printer object MUST use the value to populate the Job object'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 object's "xxx-supported"
      attribute, the Printer object MUST copy the attribute and its
      value to the Unsupported Attributes response 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 object MAY choose to populate the
      corresponding Job object attribute depending on whether the
      Printer object supports the attribute and is able to calculate
      or discern the correct value.
   "job-impressions" (integer(0:MAX))
      The client OPTIONALLY supplies this attribute.  The Printer
      object OPTIONALLY supports this attribute and the "job-
      impressions-supported" attribute (see section 4.4.31).  The
      client supplied "job-impressions" operation attribute identifies
      the total size in number of impressions of the document(s) being
      submitted (see section 4.3.18 for the complete semantics).
      See note under "job-k-octets".
   "job-media-sheets" (integer(0:MAX))
      The client OPTIONALLY supplies this attribute.  The Printer
      object OPTIONALLY supports this attribute and the "job-media-
      sheets-supported" attribute (see section 4.4.32).  The client
      supplied "job-media-sheets" operation attribute identifies the
      total number of media sheets to be produced for this job (see
      section 4.3.19 for the complete semantics).
      See note under "job-k-octets".

deBry, et al. Experimental [Page 37] RFC 2566 IPP/1.0: Model and Semantics April 1999

 Group 2: Job Template Attributes
      The client OPTIONALLY supplies a set of Job Template attributes
      as defined in section 4.2.  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
      object MUST be able to accept an empty group.
 Group 3: Document Content
      The client MUST supply the document data to be processed.
 Note: In addition to the MANDATORY parameters required for every
 operation request, the simplest Print-Job Request consists of just
 the "attributes-charset" and "attributes-natural-language" operation
 attributes; the "printer-uri" target operation attribute; the
 Document Content and nothing else.  In this simple case, the Printer
 object:
  1. creates a new Job object (the Job object contains a single

document),

  1. stores a generated Job name in the "job-name" attribute in the

natural language and charset requested (see Section 3.1.4.1) (if

     those are supported, otherwise using the Printer object's default
     natural language and charset), and
   - at job processing time, uses its corresponding default value
     attributes for the supported Job Template attributes that were
     not supplied by the client as IPP attribute or embedded
     instructions in the document data.

3.2.1.2 Print-Job Response

     The Printer object MUST return to the client the following sets
     of attributes as part of the Print-Job Response:
     Group 1: Operation Attributes
   Status Message:
      In addition to the REQUIRED status code returned in every
      response, the response OPTIONALLY includes a "status-message"
      (text) operation attribute as described in sections 14 and
      3.1.6.  If the client supplies unsupported or conflicting Job
      Template attributes or values, the Printer object MUST reject or
      accept the Print-Job request depending on the whether the client
      supplied a 'true' or 'false' value for the "ipp-attribute-
      fidelity" operation attribute.  See the Implementer's Guide
      [ipp-iig] for a complete description of the suggested steps for
      processing a create request.

deBry, et al. Experimental [Page 38] RFC 2566 IPP/1.0: Model and Semantics April 1999

   Natural Language and Character Set:
      The "attributes-charset" and "attributes-natural-language"
      attributes as described in section 3.1.4.2.
 Group 2: Unsupported Attributes
      This is a set of Operation and Job Template attributes supplied
      by the client (in the request) that are not supported by the
      Printer object or that conflict with one another (see the
      Implementer's Guide [ipp-iig]).  If the Printer object is not
      returning any Unsupported Attributes in the response, the
      Printer object SHOULD omit Group 2 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 object does not support the supplied attribute
         (no matter what the attribute syntax or value).
      2. The Printer object does support the attribute, but does not
         support some or all of the particular attribute syntaxes or
         values supplied by the client (i.e., the Printer object does
         not have those attribute syntaxes or values in its
         corresponding "xxx-supported" attribute).
      3. The Printer object 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 object
      returns the client-supplied attribute with a substituted "out-
      of-band" value of 'unsupported' indicating no support for the
      attribute itself (see the beginning of section 4.1).
      In the case of a supported attribute with one or more
      unsupported attribute syntaxes or values, the Printer object
      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 object supports the attribute but only
      supports a subset of the client-supplied attribute syntaxes or
      values, the Printer object 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

deBry, et al. Experimental [Page 39] RFC 2566 IPP/1.0: Model and Semantics April 1999

      within the same job), the Printer object 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 The Implementer's Guide [ipp-iig] for an
      example.
      In these three cases, the value of the "ipp-attribute-fidelity"
      supplied by the client does not affect what the Printer object
      returns.  The value of "ipp-attribute-fidelity" only affects
      whether the Print-Job operation is accepted or rejected.  If the
      job is accepted, the client may query the job using the Get-
      Job-Attributes operation requesting the unsupported attributes
      that were returned in the create response to see which
      attributes were ignored (not stored on the Job object) and which
      attributes were stored with other (substituted) values.
 Group 3: Job Object Attributes
   "job-uri" (uri):
      The Printer object MUST return the Job object's URI by returning
      the contents of the REQUIRED "job-uri" Job object attribute.
      The client uses the Job object's URI when directing operations
      at the Job object.  The Printer object always uses its
      configured security policy when creating the new URI.  However,
      if the Printer object supports more than one URI, the Printer
      object also uses information about which URI was used in the
      Print-Job Request to generated the new URI so that the new URI
      references the correct access channel.  In other words, if the
      Print-Job Request comes in over a secure channel, the Printer
      object MUST generate a Job URI that uses the secure channel as
      well.
   "job-id" (integer(1:MAX)):
      The Printer object MUST return the Job object's Job ID by
      returning the REQUIRED "job-id" Job object 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 object.
   "job-state":
      The Printer object MUST return the Job object's REQUIRED "job-
      state" attribute. The value of this attribute (along with the
      value of the next attribute "job-state-reasons") is taken from a
      "snapshot" of the new Job object at some meaningful point in
      time (implementation defined) between when the Printer object
      receives the Print-Job Request and when the Printer object
      returns the response.

deBry, et al. Experimental [Page 40] RFC 2566 IPP/1.0: Model and Semantics April 1999

   "job-state-reasons":
      The Printer object OPTIONALLY returns the Job object's OPTIONAL
      "job-state-reasons" attribute.  If the Printer object 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-reasons" attribute is not supported
      and will not be returned in a subsequent Job object query.
   "job-state-message":
      The Printer object OPTIONALLY returns the Job object's OPTIONAL
      "job-state-message" attribute.  If the Printer object 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 object query.
   "number-of-intervening-jobs":
      The Printer object OPTIONALLY returns the Job object's OPTIONAL
      "number-of-intervening-jobs" attribute.  If the Printer object
      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 object query.
      Note: Since any printer state information which 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 specific printer status attributes.
 Note: In addition to the MANDATORY parameters required for every
 operation response, the simplest response consists of the just the
 "attributes-charset" and "attributes-natural-language" operation
 attributes and the "job-uri", "job-id", and "job-state" Job Object
 Attributes.  In this simplest case, the status code is "successful-
 ok" and there is no "status-message" operation attribute.

3.2.2 Print-URI Operation

 This OPTIONAL operation is identical to the Print-Job operation
 (section 3.2.1) 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
 object's "referenced-uri-scheme-supported" attribute, the Printer

deBry, et al. Experimental [Page 41] RFC 2566 IPP/1.0: Model and Semantics April 1999

 object MUST reject the request and return the 'client-error-uri-
 scheme-not-supported' status code.  See The Implementer's Guide
 [ipp-iig] for suggested additional checks.  The Printer NEED NOT
 follow the reference and validate the contents of the reference.
 If the Printer object supports this operation, it MUST support the
 "reference-uri-schemes-supported" Printer attribute (see section
 4.4.24).
 It is up to the IPP object to interpret the URI and subsequently
 "pull" the document from the source referenced by the URI string.

3.2.3 Validate-Job Operation

 This REQUIRED operation is similar to the Print-Job operation
 (section 3.2.1) except that a client supplies no document data and
 the Printer allocates no resources (i.e., it does not create a new
 Job object).  This operation is used only to verify capabilities of a
 printer object 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 Print-Job operation (with the
 document data) would be accepted. The Validate-Job operation also
 performs the same security negotiation as the Print-Job operation
 (see section 8), so that a client can check that the client and
 Printer object security requirements can be met before performing a
 Print-Job operation.
 Note: 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 object returns the same status codes, Operation
 Attributes (Group 1) and Unsupported Attributes (Group 2) as the
 Print-Job operation.  However, no Job Object Attributes (Group 3) are
 returned, since no Job object is created.

3.2.4 Create-Job Operation

 This OPTIONAL operation is similar to the Print-Job operation
 (section 3.2.1) 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

deBry, et al. Experimental [Page 42] RFC 2566 IPP/1.0: Model and Semantics April 1999

 client OPTIONALLY supplies the "document-name", "document-format",
 and "document-natural-language" attributes for each document in the
 multi-document Job object.
 If a Printer object supports the Create-Job operation, it MUST also
 support the Send-Document operation and also MAY support the Send-URI
 operation.
 If the Printer object supports this operation, it MUST support the
 "multiple-operation-time-out" Printer attribute (see section 4.4.28).

3.2.5 Get-Printer-Attributes Operation

 This REQUIRED operation allows a client to request the values of the
 attributes of a Printer object.   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
 object returns a corresponding attribute set with the appropriate
 attribute values filled in.
 For Printer objects, the possible names of attribute groups are:
  1. 'job-template': all of the Job Template attributes that apply to

a Printer object (the last two columns of the table in Section

     4.2).
   - 'printer-description': the attributes specified in Section 4.4.
   - 'all': the special group 'all' that includes all supported
     attributes.
 Since a client MAY request specific attributes or named groups, there
 is a potential that there is some overlap.  For example, if a client
 requests, 'printer-name' and 'all', the client is actually requesting
 the "printer-name" attribute twice: once by naming it explicitly, and
 once by inclusion in the 'all' group.  In such cases, the Printer
 object NEED NOT return 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.
 It is NOT REQUIRED that a Printer object support all attributes
 belonging to a group (since some attributes are OPTIONAL).  However,
 it is REQUIRED that each Printer object support all group names.

deBry, et al. Experimental [Page 43] RFC 2566 IPP/1.0: Model and Semantics April 1999

3.2.5.1 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:
      attributes-charset" and "attributes-natural-language" butes as
      described in section 3.1.4.1.
   Target:
      The "printer-uri" (uri) operation attribute which is the target
      for this operation as described in section 3.1.5.
   Requesting User Name:
      The "requesting-user-name" (name(MAX)) attribute SHOULD be
      supplied by the client as described in section 8.3.
   "requested-attributes" (1setOf keyword) :
      The client OPTIONALLY supplies a set of attribute names and/or
      attribute group names in whose values the requester is
      interested.  The Printer object 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 OPTIONALLY supplies this attribute.  The Printer
      object MUST support this attribute.  This attribute is useful
      for a Printer object to determine the set of supported attribute
      values that relate to the requested document format.  The
      Printer object MUST return the attributes and values that it
      uses to validate a job on a create or Validate-Job operation in
      which this document format is supplied. The Printer object
      SHOULD return only (1) those attributes 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 object to
      eliminate the attributes and values that are not supported for a
      specific document format.  For example, a Printer object might
      have multiple interpreters to support both '
      application/postscript' (for PostScript) and 'text/plain' (for
      text) documents.  However, for only one of those interpreters
      might the Printer object be able to support "number-up" with
      values of '1', '2', and '4'.  For the other interpreter it might
      be able to only support "number-up" with a value of '1'. Thus a

deBry, et al. Experimental [Page 44] RFC 2566 IPP/1.0: Model and Semantics April 1999

      client can use the Get-Printer-Attributes operation to obtain
      the attributes and values that will be used to accept/reject a
      create job operation.
      If the Printer object does not distinguish between different
      sets of supported values for each different document format when
      validating jobs in the create and Validate-Job operations, it
      MUST NOT distinguish between different document formats in the
      Get-Printer-Attributes operation. If the Printer object 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 object
      attributes:
  1. Printer attributes that are Job Template attributes ("xxx-

default" "xxx-supported", and "xxx-ready" in the Table in

        Section 4.2),
     - "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"
      The values of all other Printer object attributes (including
      "document-format-supported") remain invariant with respect to
      the client supplied document format (except for new Printer
      description attribute as registered according to section 6.2).
      If the client omits this "document-format" operation attribute,
      the Printer object MUST respond as if the attribute had been
      supplied with the value of the Printer object's "document-
      format-default" attribute.  It is recommended that the client
      always supply a value for "document-format", since the Printer
      object's "document-format-default" may 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 4.1.9.
      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 object's "document-
      format-supported" attribute, the Printer object MUST reject the
      operation and return the 'client-error-document-format-not-
      supported' status code.

deBry, et al. Experimental [Page 45] RFC 2566 IPP/1.0: Model and Semantics April 1999

3.2.5.2 Get-Printer-Attributes Response

 The Printer object returns the following sets of attributes as part
 of the Get-Printer-Attributes Response:
 Group 1: Operation Attributes
   Status Message:
      In addition to the REQUIRED status code returned in every
      response, the response OPTIONALLY includes a "status-message"
      (text) operation attribute as described in section 3.1.6.
   Natural Language and Character Set:
      The "attributes-charset" and "attributes-natural-language"
      attributes as described in section 3.1.4.2.
 Group 2: Unsupported Attributes
      This is a set of Operation attributes supplied by the client (in
      the request) that are not supported by the Printer object or
      that conflict with one another (see sections 3.2.1.2 and 16).
      The response NEED NOT contain the "requested-attributes"
      operation attribute with any supplied values (attribute
      keywords) that were requested by the client but are not
      supported by the IPP object.  If the Printer object is not
      returning any Unsupported Attributes in the response, the
      Printer object SHOULD omit Group 2 rather than sending an empty
      group.  However, a client MUST be able to accept an empty group.
 Group 3: Printer Object Attributes
      This is the set of requested attributes and their current
      values.  The Printer object ignores (does not respond with) any
      requested attribute which is not supported.  The Printer object
      MAY respond with a subset of the supported attributes and
      values, depending on the security policy in force.  However, the
      Printer object MUST respond with the 'unknown' value for any
      supported attribute (including all REQUIRED attributes) for
      which the Printer object does not know the value.  Also the
      Printer object MUST respond with the 'no-value' for any
      supported attribute (including all REQUIRED attributes) for
      which the system administrator has not configured a value.  See
      the description of the "out-of-band" values in the beginning of
      Section 4.1.

deBry, et al. Experimental [Page 46] RFC 2566 IPP/1.0: Model and Semantics April 1999

3.2.6 Get-Jobs Operation

 This REQUIRED operation allows a client to retrieve the list of Job
 objects belonging to the target Printer object.  The client may also
 supply a list of Job attribute names and/or attribute group names.  A
 group of Job object attributes will be returned for each Job object
 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 object (see the description of Job attribute group names in
 section 3.3.4).

3.2.6.1 Get-Jobs Request

 The client submits the Get-Jobs request to a Printer object.
 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 3.1.4.1.
   Target:
      The "printer-uri" (uri) operation attribute which is the target
      for this operation as described in section 3.1.5.
   Requesting User Name:
      The "requesting-user-name" (name(MAX)) attribute SHOULD be
      supplied by the client as described in section 8.3.
   "limit" (integer(1:MAX)):
      The client OPTIONALLY supplies this attribute.  The Printer
      object MUST support this attribute. It is an integer value that
      indicates a limit to the number of Job objects 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.  There is no mechanism to allow for the
      next 'M' jobs after the first 'N' jobs.  If the client does not
      supply this attribute, the Printer object responds with all
      applicable jobs.
   "requested-attributes" (1setOf keyword):
      The client OPTIONALLY supplies this attribute.  The Printer
      object MUST support this attribute.  It is a set of Job
      attribute names and/or attribute groups names in whose values

deBry, et al. Experimental [Page 47] RFC 2566 IPP/1.0: Model and Semantics April 1999

      the requester is interested.  This set of attributes is returned
      for each Job object that is returned.  The allowed attribute
      group names are the same as those defined in the Get-Job-
      Attributes operation in section 3.3.4.  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'.
   "which-jobs" (type2 keyword):
      The client OPTIONALLY supplies this attribute.  The Printer
      object MUST support this attribute.  It indicates which Job
      objects MUST be returned by the Printer object. The values for
      this attribute are:
        'completed': This includes any Job object whose state is
           'completed', 'canceled', or 'aborted'.
        'not-completed': This includes any Job object whose state is '
           pending', 'processing', 'processing-stopped', or 'pending-
           held'.
      A Printer object MUST support both values.  However, if the
      mentation does not keep jobs in the 'completed', 'canceled', '
      aborted' states, then it returns no jobs when the 'completed'
      value is supplied.
      If a client supplies some other value, the Printer object MUST
      copy the attribute and the unsupported value to the Unsupported
      Attributes response 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 object
      MUST respond as if the client had supplied the attribute with a
      value of 'not-completed'.
   "my-jobs" (boolean):
      The client OPTIONALLY supplies this attribute.  The Printer
      object MUST support this attribute.  It indicates whether all
      jobs or just the jobs submitted by the requesting user of this
      request  MUST be returned by the Printer object.  If the client
      does not supply this attribute, the Printer object MUST respond
      as if the client had supplied the attribute with a value of '
      false', i.e., all jobs.  The means for authenticating the
      requesting user and matching the jobs is described in section 8.

deBry, et al. Experimental [Page 48] RFC 2566 IPP/1.0: Model and Semantics April 1999

3.2.6.2 Get-Jobs Response

 The Printer object returns all of the Job objects that match the
 criteria as defined by the attribute values supplied by the client in
 the request.  It is possible that no Job objects are returned since
 there may literally be no Job objects at the Printer, or there may be
 no Job objects that match the criteria supplied by the client.  If
 the client requests any Job attributes at all, there is a set of Job
 Object Attributes returned for each Job object.
 Group 1: Operation Attributes
   Status Message:
      In addition to the REQUIRED status code returned in every
      response, the response OPTIONALLY includes a "status-message"
      (text) operation attribute as described in sections 14 and
      3.1.6.
   Natural Language and Character Set:
      The "attributes-charset" and "attributes-natural-language"
      attributes as described in section 3.1.4.2.
 Group 2: Unsupported Attributes
      This is a set of Operation attributes supplied by the client (in
      the request) that are not supported by the Printer object or
      that conflict with one another (see sections 3.2.1.2 and the
      Implementer's Guide [ipp-iig]).  The response NEED NOT contain
      the "requested-attributes" operation attribute with any supplied
      values (attribute keywords) that were requested by the client
      but are not supported by the IPP object.  If the Printer object
      is not returning any Unsupported Attributes in the response, the
      Printer object SHOULD omit Group 2 rather than sending an empty
      group.  However, a client MUST be able to accept an empty group.
 Groups 3 to N: Job Object Attributes
      The Printer object responds with one set of Job Object
      Attributes for each returned Job object.  The Printer object
      ignores (does not respond with) any requested attribute or value
      which is not supported or which 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 8).  However, the Printer object MUST respond with the '
      unknown' value for any supported attribute (including all
      REQUIRED attributes) for which the Printer object does not know

deBry, et al. Experimental [Page 49] RFC 2566 IPP/1.0: Model and Semantics April 1999

      the value, unless it would violate the security policy.  See the
      description of the "out-of-band" values in the beginning of
      Section 4.1.
      Jobs are returned in the following order:
  1. 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
          object).

3.3 Job Operations

 All Job operations are directed at Job objects.  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 MAY
 either be a single Job URI or a combination of a Printer URI with a
 Job ID.  The IPP object implementation MUST support both forms of
 identification for every job.

3.3.1 Send-Document Operation

 This OPTIONAL operation allows a client to create a multi-document
 Job object that is initially "empty" (contains no documents).  In the
 Create-Job response, the Printer object returns the Job object's URI
 (the "job-uri" attribute) and the Job object'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.
 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 an IPP Printer defined minimum time interval after
 the receipt of the previous request for the job.  If a Printer object
 supports multiple document jobs, the Printer object MUST support the
 "multiple-operation-time-out" attribute (see section 4.4.28).  This
 attribute indicates the minimum number of seconds the Printer object
 will wait for the next send operation before taking some recovery
 action.

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 An IPP object MUST recover from an errant client that does not supply
 a send operation, sometime after the minimum time interval specified
 by the Printer object's "multiple-operation-time-out" attribute.
 Such recovery MAY include any of the following 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
      4.3.8), if supported, and clean up all resources associated with
      the Job.  In this case, if another send operation is finally
      received, the Printer responds with an "client-error-not-
      possible" or "client-error-not-found" depending on whether or
      not the Job object is still around when the send operation
      finally arrives.
   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 object, 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, close the Job, but move it to the 'pending-held'
      and add the 'submission-interrupted' value to the job's "job-
      state-reasons" attribute (see section 4.3.8), if supported.
      This action allows the user or an operator to determine whether
      to continue processing the Job by moving it back to the '
      pending' state or to cancel the job.
 Each implementation is free to decide the "best" action to take
 depending on 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
 object, it is possible that the Job object may already have been
 processed to the point that some media sheet pages have been printed.

3.3.1.1 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 3.1.4.1.

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   Target:
      Either (1) the "printer-uri" (uri) plus "job-id"
      (integer(1:MAX))or (2) the "job-uri" (uri) operation
      attribute(s) which define the target for this operation as
      described in section 3.1.5.
   Requesting User Name:
      "requesting-user-name" (name(MAX)) attribute SHOULD be supplied
      by the client as described in section 8.3.
   "document-name" (name(MAX)):
      The client OPTIONALLY supplies this attribute.  The Printer
      object MUST support this attribute.  It contains the client
      supplied document name.  The document name MAY be different than
      the Job name.  It might be helpful, but NEED NOT 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 3.2.1.1)
      for more information about this attribute
 "document-format" (mimeMediaType):
      The client OPTIONALLY supplies this attribute.  The Printer
      object MUST support this attribute.  The value of this attribute
      identifies the format of the supplied document data.  If the
      client does not supply this attribute, the Printer object
      assumes that the document data is in the format defined by the
      Printer object's "document-format-default" attribute.  If the
      client supplies this attribute, but the value is not supported
      by the Printer object, i.e., the value is not one of the values
      of the Printer object's "document-format-supported" attribute,
      the Printer object MUST reject the request and return the '
      client-error-document-format-not-supported' status code.
   "document-natural-language" (naturalLanguage):
      The client OPTIONALLY supplies this attribute.  The Printer
      object OPTIONALLY supports this attribute.  This attribute
      specifies the natural language of the document for those
      document-formats that require a specification of the natural
      language in order to image the document unambiguously.  There
      are no particular values required for the Printer object to
      support.
   "compression" (type3 keyword)
      The client OPTIONALLY supplies this attribute.  The Printer
      object OPTIONALLY supports this attribute and the "compression-
      supported" attribute (see section 4.4.29).  The client supplied

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      "compression" operation attribute identifies the compression
      algorithm used on the document data.  If the client omits this
      attribute, the Printer object MUST assume that the data is not
      compressed.  If the client supplies the attribute and the
      Printer object supports the attribute, the Printer object MUST
      use the corresponding decompression algorithm on the document
      data. If the client supplies this attribute, but the value is
      not supported by the Printer object, i.e., the value is not one
      of the values of the Printer object's "compression-supported"
      attribute, the Printer object MUST copy the attribute and its
      value to the Unsupported Attributes response group, reject the
      request, and return the 'client-error-attributes-or-values-not-
      supported' status code.
   "last-document" (boolean):
      The client MUST supply this attribute.  The Printer object MUST
      support this attribute. It is a boolean flag that is set to '
      true' if this is the last document for the Job, 'false'
      otherwise.
 Group 2: Document Content
      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 object's "number-of-documents" attribute, since
      no real document was added to the job.

3.3.1.2 Send-Document Response

 The following sets of attributes are part of the Send-Document
 Response:
 Group 1: Operation Attributes
   Status Message:
      In addition to the REQUIRED status code returned in every
      response, the response OPTIONALLY includes a "status-message"
      (text) operation attribute as described in sections 14 and
      3.1.6.
   Natural Language and Character Set:
      The "attributes-charset" and "attributes-natural-language"
      attributes as described in section 3.1.4.2.

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 Group 2: Unsupported Attributes
      This is a set of Operation attributes supplied by the client (in
      the request) that are not supported by the Printer object or
      that conflict with one another (see sections 3.2.1.2 and the
      Implementer's Guide [ipp-iig]).  If the Printer object is not
      returning any Unsupported Attributes in the response, the
      Printer object SHOULD omit Group 2 rather than sending an empty
      group.  However, a client MUST be able to accept an empty group.
 Group 3: Job Object Attributes
      This is the same set of attributes as described in the Print-Job
      response (see section 3.2.1.2).

3.3.2 Send-URI Operation

 This OPTIONAL operation is identical to the Send-Document operation
 (see section 3.3.1) except that a client MUST supply a URI reference
 ("document-uri" operation attribute) rather than the document data
 itself.  If a Printer object supports this operation, clients can use
 both Send-URI or Send-Document operations to add new documents to an
 existing multi-document Job object.  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 object supports this operation, it MUST also support the
 Print-URI operation (see section 3.2.2).
 The Printer object MUST validate the syntax and URI scheme of the
 supplied URI before returning a response, just as in the Print-URI
 operation.

3.3.3 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.

3.3.3.1 Cancel-Job Request

 The following groups of attributes are part of the Cancel-Job
 Request:

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 Group 1: Operation Attributes
   Natural Language and Character Set:
      The "attributes-charset" and "attributes-natural-language"
      attributes as described in section 3.1.4.1.
   Target:
      Either (1) the "printer-uri" (uri) plus "job-id"
      (integer(1:MAX))or (2) the "job-uri" (uri) operation
      attribute(s) which define the target for this operation as
      described in section 3.1.5.
   Requesting User Name:
      The "requesting-user-name" (name(MAX)) attribute SHOULD be
      supplied by the client as described in section 8.3.
   "message" (text(127)):
      The client OPTIONALLY supplies this attribute.  The Printer
      object OPTIONALLY supports 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.  It is an implementation decision of
      how or where to display this message to the operator (if at
      all).

3.3.3.2 Cancel-Job Response

 The following sets of attributes are part of the Cancel-Job Response:
 Group 1: Operation Attributes
   Status Message:
      In addition to the REQUIRED status code returned in every
      response, the response OPTIONALLY includes a "status-message"
      (text) operation attribute as described in sections 14 and
      3.1.6.
      If the job is already in the 'completed', 'aborted', or '
      canceled' state, or the 'process-to-stop-point' value is set in
      the Job's "job-state-reasons" attribute, the Printer object MUST
      reject the request and return the 'client-error-not-possible'
      error status code.

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   Natural Language and Character Set:
      The "attributes-charset" and "attributes-natural-language"
      attributes as described in section 3.1.4.2.
 Group 2: Unsupported Attributes
      This is a set of Operation attributes supplied by the client (in
      the request) that are not supported by the Printer object or
      that conflict with one another (see section 3.2.1.2 and the
      Implementer's Guide [ipp-iig]).  If the Printer object is not
      returning any Unsupported Attributes in the response, the
      Printer object SHOULD omit Group 2 rather than sending an empty
      group.  However, a client MUST be able to accept an empty group.
 Once a successful response has been sent, the implementation
 guarantees that the Job will eventually end up in the 'canceled'
 state. Between the time of the Cancel-Job operation is accepted and
 when the job enters the 'canceled' job-state (see section 4.3.7), 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.

3.3.4 Get-Job-Attributes Operation

 This REQUIRED operation allows a client to request the values of
 attributes of a Job object and it is almost identical to the Get-
 Printer-Attributes operation (see section 3.2.5).  The only
 differences are that the operation is directed at a Job object rather
 than a Printer object, there is no "document-format" operation
 attribute used when querying a Job object, and the returned attribute
 group is a set of Job object attributes rather than a set of Printer
 object attributes.
 For Jobs, the possible names of attribute groups are:
  1. 'job-template': all of the Job Template attributes that apply to a

Job object (the first column of the table in Section 4.2).

  1. 'job-description': all of the Job Description attributes specified

in Section 4.3.

  1. 'all': the special group 'all' that includes all supported

attributes.

 Since a client MAY request specific attributes or named groups, there
 is a potential that there is 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

deBry, et al. Experimental [Page 56] RFC 2566 IPP/1.0: Model and Semantics April 1999

 Printer object NEED NOT return 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.
 It is NOT REQUIRED that a Job object support all attributes belonging
 to a group (since some attributes are OPTIONAL).  However it is
 REQUIRED that each Job object support all group names.

3.3.4.1 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 object:
 Group 1: Operation Attributes
   Natural Language and Character Set:
      The "attributes-charset" and "attributes-natural-language"
      attributes as described in section 3.1.4.1.
   Target:
      Either (1) the "printer-uri" (uri) plus "job-id"
      (integer(1:MAX)) or (2) the "job-uri" (uri) operation
      attribute(s) which define the target for this operation as
      described in section 3.1.5.
   Requesting User Name:
      The "requesting-user-name" (name(MAX)) attribute SHOULD be
      supplied by the client as described in section 8.3.
   "requested-attributes" (1setOf keyword) :
      The client OPTIONALLY supplies this attribute.  The IPP object
      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 IPP object
      MUST respond as if this attribute had been supplied with a value
      of 'all'.

3.3.4.2 Get-Job-Attributes Response

 The Printer object returns the following sets of attributes as part
 of the Get-Job-Attributes Response:

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 Group 1: Operation Attributes
   Status Message:
      In addition to the REQUIRED status code returned in every
      response, the response OPTIONALLY includes a "status-message"
      (text) operation attribute as described in sections 14 and
      3.1.6.
   Natural Language and Character Set:
      The "attributes-charset" and "attributes-natural-language"
      attributes as described in section 3.1.4.2.  The "attributes-
      natural-language" MAY be the natural language of the Job object,
      rather than the one requested.
 Group 2: Unsupported Attributes
      This is a set of Operation attributes supplied by the client (in
      the request) that are not supported by the Printer object or
      that conflict with one another (see sections 3.2.1.2 and the
      Implementer's Guide [ipp-iig]).  The response NEED NOT contain
      the "requested-attributes" operation attribute with any supplied
      values (attribute keywords) that were requested by the client
      but are not supported by the IPP object.  If the Printer object
      is not returning any Unsupported Attributes in the response, the
      Printer object SHOULD omit Group 2 rather than sending an empty
      group.  However, a client MUST be able to accept an empty group.
 Group 3: Job Object Attributes
      This is the set of requested attributes and their current
      values.  The IPP object ignores (does not respond with) any
      requested attribute or value which is not supported or which 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 8).  However, the IPP
      object MUST respond with the 'unknown' value for any supported
      attribute (including all RED butes) for which the IPP object
      does not know the value, s it would violate the security policy.
      See the description e "out-of-band" values in the beginning of
      Section 4.1.

4. 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 which
 are included within the scope of this protocol.  Many of these
 attributes are derived from other relevant specifications:

deBry, et al. Experimental [Page 58] RFC 2566 IPP/1.0: Model and Semantics April 1999

  1. Document Printing Application (DPA) [ISO10175]
  2. RFC 1759 Printer MIB [RFC1759]
 Each attribute is uniquely identified in this document using a
 "keyword" (see section 12.2.1) which is the name of the attribute.
 The keyword is included in the section header 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.

4.1 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 3 and
 4 includes the name of attribute syntax(es) in the heading (in
 parentheses).  A conforming implementation of an attribute MUST
 include the semantics of the attribute syntax(es) so identified.
 Section 6.3 describes how the protocol can be extended with new
 attribute syntaxes.
 The attribute syntaxes are specified in the following sub-sections,
 where the sub-section heading 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 sub-section heading 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.  Standard
 "out-of-band" values are:
   'unknown': The attribute is supported by the IPP object, but the
      value is unknown to the IPP object for some reason.
   '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.
   'no-value': The attribute is supported by the Printer object, but
      the system administrator has not yet configured a value.
 The Encoding and Transport specification [RFC2565] defines mechanisms
 for passing "out-of-band" values.  All attributes in a request MUST
 have one or more values as defined in Sections 4.2 to 4.4.  Thus
 clients MUST NOT supply attributes with "out-of-band" values.  All
 attribute in a response MUST have one or more values as defined in
 Sections 4.2 to 4.4 or a single "out-of-band" value.

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 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 sub-section heading to indicate the choice.
 Since each value MUST be tagged as to its attribute syntax in the
 protocol, a single-valued attribute instance may have any one of its
 attribute syntaxes and a multi-valued attribute instance may have a
 mixture of its defined attribute syntaxes.

4.1.1 '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.
 In this specification, 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
 specification 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, objects and clients accept and return only one of
 the two syntax 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 3.1.4 or "attributes-natural-language" job attribute defined
 in section 4.3.24, 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

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 Printer object 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 object uses the
 attribute syntax 'textWithLanguage' for text attributes (this is the
 Natural Language Override mechanism described in section 3.1.4).
 The 'textWithoutLanguage' and 'textWithLanguage' attribute syntaxes
 are described in more detail in the following sections.

4.1.1.1 'textWithoutLanguage'

 The 'textWithoutLanguage' syntax indicates a value that is sequence
 of zero or more characters.  Text strings are encoded using the rules
 of some charset.  The Printer object MUST support the UTF-8 charset
 [RFC2279] and MAY support additional charsets to represent 'text'
 values, provided that the charsets are registered with IANA [IANA-
 CS].  See Section 4.1.7 for the specification of the 'charset'
 attribute syntax, including restricted semantics and examples of
 charsets.

4.1.1.2 'textWithLanguage'

 The 'textWithLanguage' attribute syntax is a compound attribute
 syntax consisting of two parts: a 'textWithoutLanguage' part plus an
 additional 'naturalLanguage' (see section 4.1.8) part that overrides
 the natural language in force.  The 'naturalLanguage' part explicitly
 identifies the natural language that applies to the text part of that
 value and that value alone.  For any give text attribute, the '
 textWithoutLanguage' part is limited to the maximum length defined
 for that attribute, but the 'naturalLanguage' part is always limited
 to 63 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 create request, the Printer object MUST accept and store with
 the Job object any natural language in the "attributes-natural-
 language" operation attribute, whether the Printer object supports
 that natural language or not.  Furthermore, the Printer object MUST
 accept and store any 'textWithLanguage' attribute value, whether the

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 Printer object 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 [RFC2565] for a detailed
 example of the 'textWithLanguage' attribute syntax.

4.1.2 '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.
 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, objects and clients accept and return only one of
 the two syntax per attribute.  The syntax 'name' never appears "on-
 the-wire".
 Note: Only the 'text' and 'name' attribute syntaxes permit the
 Natural Language Override mechanism.
 Some attributes are defined as 'type3 keyword | name'.  These
 attributes support values that are either type3 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.

4.1.2.1 'nameWithoutLanguage'

 The 'nameWithoutLanguage' syntax indicates a value that is sequence
 of zero or more characters so that its encoded form does not exceed
 MAX octets.

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4.1.2.2 'nameWithLanguage'

 The 'nameWithLanguage' attribute syntax is a compound attribute
 syntax consisting of two parts: a 'nameWithoutLanguage' part plus an
 additional 'naturalLanguage' (see section 4.1.8) 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.
 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.
 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

4.1.2.3 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 object'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 3.1.4.1) match.  The
      matching rules are:
           a. the name parts match if the two names are identical
           character by character, except it is RECOMMENDED that case
           be ignored.  For example: 'Ajax-letter-head-white' MUST
           match 'Ajax-letter-head-white' and SHOULD match 'ajax-
           letter-head-white' and 'AJAX-LETTER-HEAD-WHITE'.
           b. the Associated Natural-Language parts match if the
           shorter of the two meets the syntactic requirements of RFC
           1766 [RFC1766] and matches byte for byte with the longer.
           For example, 'en' matches 'en', 'en-us' and 'en-gb', but

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           matches neither 'fr' nor 'e'.

4.1.3 'keyword'

 The 'keyword' attribute syntax is a sequence of characters, length: 1
 to 255, containing only the US-ASCII [ASCII] 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 U.S. 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 U.S. 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 which 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 U.S. English,
 they MAY be mapped to other U.S. English words for U.S. 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 defined keyword values for that attribute are listed.
 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
 different semantic ideas for each attribute.  Section 6.1 describes
 how the protocol can be extended with new keyword values.  Examples
 of attribute name keywords:
   "job-name"
   "attributes-charset"
 Note:  This document uses "type1", "type2", and "type3" prefixes to
 the "keyword" basic syntax to indicate different levels of review for
 extensions (see section 6.1).

deBry, et al. Experimental [Page 64] RFC 2566 IPP/1.0: Model and Semantics April 1999

4.1.4 '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 are 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 specification are also used for
 corresponding attributes in other standards [RFC1759].  This syntax
 type is not used for attributes to which the system administrator may
 assign values.  Section 6.1 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 which 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 U.S.
 English, they MAY be mapped to other U.S. English words for U.S.
 English users, since the user interface is outside the scope of this
 document.
 Note: 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 4.1.  Therefore, attributes
 of type 'enum' start at '3'.
 Note:  This document uses "type1", "type2", and "type3" prefixes to
 the "enum" basic syntax to indicate different levels of review for
 extensions (see section 6.1).

4.1.5 'uri'

 The 'uri' attribute syntax is any valid Uniform Resource Identifier
 or URI [RFC2396].  Most often, URIs are simply Uniform Resource
 Locators or 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 lower-cased values, this attribute syntax type
 conforms to the case-sensitive and case-insensitive rules specified
 in [RFC2396].

4.1.6 'uriScheme'

 The 'uriScheme' attribute syntax is a sequence of characters
 representing a URI scheme according to RFC 2396 [RFC2396].  Though
 RFC 2396 requires that the values be case-insensitive, IPP requires

deBry, et al. Experimental [Page 65] RFC 2566 IPP/1.0: Model and Semantics April 1999

 all lower case values in IPP attributes to simplify comparing by IPP
 clients and Printer objects.  Standard values for this syntax type
 are the following keywords:
   'http':  for HTTP schemed URIs (e.g., "http:...")
   'https':  for use with HTTPS schemed URIs (e.g., "https:...")
      (not on IETF standards track)
   'ftp': for FTP schemed URIs (e.g., "ftp:...")
   'mailto': for SMTP schemed URIs (e.g., "mailto:...")
   'file': for file schemed URIs (e.g., "file:...")
 A Printer object 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.

4.1.7 '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 and 'text'
 and 'name' attribute values.  The syntax and semantics of this
 attribute syntax are specified in RFC 2046 [RFC2046] and contained in
 the IANA character-set Registry [IANA-CS] according to the IANA
 procedures [RFC2278].  Though RFC 2046 requires that the values be
 case-insensitive US-ASCII, IPP requires all lower case values in IPP
 attributes to simplify comparing by IPP clients and Printer objects.
 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:
   'utf-8':  ISO 10646 Universal Multiple-Octet Coded Character Set
      (UCS) represented as the UTF-8 [RFC2279] transfer encoding
      scheme in which US-ASCII is a subset charset.
   'us-ascii':  7-bit American Standard Code for Information
      Interchange (ASCII), ANSI X3.4-1986 [ASCII].  That standard
      defines US-ASCII, but RFC 2045 [RFC2045] eliminates most of the
      control characters from conformant usage in MIME and IPP.
   'iso-8859-1':  8-bit One-Byte Coded Character Set, Latin Alphabet
      Nr 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.

deBry, et al. Experimental [Page 66] RFC 2566 IPP/1.0: Model and Semantics April 1999

   'iso-10646-ucs-2':  ISO 10646 Universal Multiple-Octet Coded
      Character Set (UCS) represented as two octets (UCS-2), with the
      high order octet of each pair coming first (so-called Big Endian
      integer).
 Some attribute descriptions MAY place additional requirements on
 charset values that may 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.

4.1.8 'naturalLanguage'

 The 'naturalLanguage' attribute syntax is a standard identifier for a
 natural language and optionally a country.  The values for this
 syntax type are defined by RFC 1766 [RFC1766].  Though RFC 1766
 requires that the values be case-insensitive US-ASCII, IPP requires
 all lower case to simplify comparing by IPP clients and Printer
 objects.  Examples include:
   'en':  for English
   'en-us': for US English
   'fr': for French
   'de':  for German
 The maximum length of 'naturalLanguage' values used to represent IPP
 attribute values is 63 octets.

4.1.9 '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 2048 [RFC2048] for
 identifying a document format.  The value MAY include a charset
 parameter, depending on the specification of the Media Type in the
 IANA Registry [IANA-MT].  Although most other IPP syntax types allow
 for only lower-cased values, this syntax type allows for mixed-case
 values which are case-insensitive.
 Examples are:
   'text/html': An HTML document
   '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].
   'text/plain; charset=US-ASCII':  A plain text document in US-ASCII
      [52, 56].
   'text/plain; charset=ISO-8859-1':  A plain text document in ISO
      8859-1 (Latin 1) [ISO8859-1].

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   'text/plain; charset=utf-8':  A plain text document in ISO 10646
      represented as UTF-8 [RFC2279]
   'text/plain, charset=iso-10646-ucs-2':  A plain text document in
      ISO 10646 represented in two octets (UCS-2) [ISO10646-1]
   'application/postscript':  A PostScript document [RFC2046]
   'application/vnd.hp-PCL':  A PCL document [IANA-MT] (charset escape
      sequence embedded in the document data)
   'application/octet-stream':  Auto-sense - see below
 One special type is 'application/octet-stream'.  If the Printer
 object supports this value, the Printer object MUST be capable of
 auto-sensing the format of the document data.  If the Printer
 object's default value attribute "document-format-default" is set to
 'application/octet-stream', the Printer object 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 may be '
      application/octet-stream' indicating an auto-sensing mechanism).
   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 object MUST trust
      the client supplied value more than the outcome of applying an
      automatic format detection mechanism.  For example, the client
      may be requesting the printing of a PostScript file as a '
      text/plain' document.  The Printer object 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 object MUST use its
      auto-sensing mechanism on the client supplied document data
      whether auto-sensing is the Printer object'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 object 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 be used.
 The maximum length of a 'mimeMediaType' value to represent IPP
 attribute values is 255 octets.

deBry, et al. Experimental [Page 68] RFC 2566 IPP/1.0: Model and Semantics April 1999

4.1.10 'octetString'

 The 'octetString' attribute syntax is a sequence of octets encoded in
 a maximum of 1023 octets which is indicated in sub-section headers
 using the notation: octetString(MAX).  This syntax type is used for
 opaque data.

4.1.11 'boolean'

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

4.1.12 '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 may specify the range constraint explicitly in sub-section
 headers 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.  However, the enforcement of that
 additional constraint is up to the IPP objects, not the protocol.

4.1.13 '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 header description for an
 attribute in this document whose attribute syntax is 'rangeOfInteger'
 (i.e., 'X:Y' indicating X as a minimum value and Y as a maximum
 value), then the constraint applies to both integers.

4.1.14 '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  which are localized to the natural
 language and date format of the user.

4.1.15 'resolution'

 The 'resolution' attribute syntax specifies a two-dimensional
 resolution in the indicated units.  It consists of 3 values: a cross
 feed direction resolution (positive integer value), a feed direction

deBry, et al. Experimental [Page 69] RFC 2566 IPP/1.0: Model and Semantics April 1999

 resolution (positive integer value), and a units value.  The
 semantics of these three components are taken from the Printer MIB
 [RFC1759] suggested values.  That is, the cross feed direction
 component resolution component is the same as the
 prtMarkerAddressabilityXFeedDir object in the Printer MIB, the feed
 direction component 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.  Example:  '300', '600', '
 3' indicates a 300 dpi cross-feed direction resolution, a 600 dpi
 feed direction resolution, since a '3' indicates dots per inch (dpi).

4.1.16 '1setOf X'

 The '1setOf  X' attribute syntax is 1 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 may specify that the values MUST be in a
 certain order for that attribute.

4.2 Job Template Attributes

 Job Template attributes describe job processing behavior.  Support
 for Job Template attributes by a Printer object is OPTIONAL (see
 section 13.2.3 for a description of support for OPTIONAL attributes).
 Also, clients OPTIONALLY supply Job Template attributes in create
 requests.
 Job Template attributes conform to the following rules.  For each Job
 Template attribute called "xxx":
   1. If the Printer object supports "xxx" then it MUST support both a
      "xxx-default" attribute (unless there is a "No" in the table
      below) and a "xxx-supported" attribute.  If the Printer object
      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" may be supported for some document formats
      and not supported for other document formats.  For example, it
      is expected that a Printer object 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. "xxx" is OPTIONALLY supplied by the client in a create 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 object 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.
      Note: Since an administrator MAY change the default value
      attribute after a Job object has been submitted but before it
      has been processed, the default value used by the Printer object
      at job processing time may be different that the default value
      in effect at job submission time.
   3. The "xxx-supported" attribute is a Printer object attribute that
      describes which job processing behaviors are supported by that
      Printer object.  A client can query the Printer object 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 "job-sheet-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 create 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 object for its supported value attributes.  The
 application SHOULD also query the default value attributes.  If the
 application then limits selectable values to only those value that
 are supported, the application can guarantee that the values supplied
 by the client in the create 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).

deBry, et al. Experimental [Page 71] RFC 2566 IPP/1.0: Model and Semantics April 1999

 The "finishings" attribute is an example of a Job Template attribute.
 It can take on a set of values such as 'staple', 'punch', and/or '
 cover'.  A client can query the Printer object 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 create request and the document data does not contain any
 corresponding finishing instructions.  If the client does supply the
 "finishings" attribute in the create request, the IPP object
 validates the value or values to make sure that they are a subset of
 the supported values identified in the Printer object's "finishings-
 supported" attribute.  See section 3.2.1.2.
 The table 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 object. These are the attributes that can optionally be
 supplied by the client in a create request.   The last two columns
 (labeled "Printer: Default Value Attribute" and "Printer: Supported
 Values Attribute") shows the name and syntax for each Job Template
 attribute in the Printer object (the default value attribute and the
 supported values attribute).  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 Value|  Printer: Supported  |
   |                   |   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-       |
   | (type3 keyword |  |  default             | supported            |
   |    name)          |  (type3 keyword |    |(1setOf               |
   |                   |    name)             | type3 keyword | name)|
   +-------------------+----------------------+----------------------+
   | job-sheets        | job-sheets-default   |job-sheets-supported  |
   | (type3 keyword |  | (type3 keyword |     |(1setOf               |
   |    name)          |    name)             | type3 keyword | name)|
   +-------------------+----------------------+----------------------+
   |multiple-document- |multiple-document-    |multiple-document-    |
   | handling          | handling-default     |handling-supported    |
   | (type2 keyword)   | (type2 keyword)      |(1setOf type2 keyword)|
   +-------------------+----------------------+----------------------+

deBry, et al. Experimental [Page 72] RFC 2566 IPP/1.0: Model and Semantics April 1999

   +===================+======================+======================+
   | Job Attribute     |Printer: Default Value|  Printer: Supported  |
   |                   |   Attribute          |   Values Attribute   |
   +===================+======================+======================+
   | copies            | copies-default       | copies-supported     |
   | (integer (1:MAX)) | (integer (1:MAX))    | (rangeOfInteger      |
   |                   |                      |       (1:MAX))       |
   +-------------------+----------------------+----------------------+
   | finishings        | finishings-default   | finishings-supported |
   |(1setOf type2 enum)|(1setOf type2 enum)   |(1setOf type2 enum)   |
   +-------------------+----------------------+----------------------+
   | page-ranges       | No                   | page-ranges-         |
   | (1setOf           |                      | supported (boolean)  |
   |   rangeOfInteger  |                      |                      |
   |        (1:MAX))   |                      |                      |
   +-------------------+----------------------+----------------------+
   | sides             | sides-default        | sides-supported      |
   | (type2 keyword)   | (type2 keyword)      |(1setOf 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-requested-|orientation-requested-|
   |  requested        |  default             |  supported           |
   |   (type2 enum)    |  (type2 enum)        |  (1setOf type2 enum) |
   +-------------------+----------------------+----------------------+
   | media             | media-default        | media-supported      |
   | (type3 keyword |  | (type3 keyword |     |(1setOf               |
   |    name)          |    name)             | type3 keyword | name)|
   |                   |                      |                      |
   |                   |                      | media-ready          |
   |                   |                      |(1setOf               |
   |                   |                      | type3 keyword | name)|
   +-------------------+----------------------+----------------------+
   | printer-resolution| printer-resolution-  | printer-resolution-  |
   | (resolution)      |  default             | supported            |
   |                   | (resolution)         |(1setOf resolution)   |
   +-------------------+----------------------+----------------------+
   | print-quality     | print-quality-default| print-quality-       |
   | (type2 enum)      | (type2 enum)         | supported            |
   |                   |                      |(1setOf type2 enum)   |
   +-------------------+----------------------+----------------------+

deBry, et al. Experimental [Page 73] RFC 2566 IPP/1.0: Model and Semantics April 1999

4.2.1 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.
 If the Printer object 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 object.  If privileged jobs are
 implemented outside IPP/1.0, 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 object, the Printer object MUST use the
 value of the Printer object's "job-priority-default" 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" is also integer(1:100).
 This single integer value indicates the number of priority levels
 supported.  The Printer object MUST take the value supplied by the
 client and map it to the closest integer in a sequence of n integers
 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.
 If the value of the Printer object's "job-priority-supported" is 10
 and the client supplies values in the range 1 to 10, the Printer
 object maps them to 5, in the range 11 to 20, the Printer object maps
 them to 15, etc.

deBry, et al. Experimental [Page 74] RFC 2566 IPP/1.0: Model and Semantics April 1999

4.2.2 job-hold-until (type3 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:
   'no-hold': immediately, if there are not other reasons to hold the
      job
   'day-time': during the day
   'evening': evening
   'night': night
   'weekend': weekend
   'second-shift': second-shift (after close of business)
   'third-shift': third-shift (after midnight)
 An administrator MUST associate allowable print times with a named
 time period (by means outside IPP/1.0).  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 MUST add the 'job-hold-until-specified' value to
 the job's "job-state-reasons" attribute, 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-reason" attribute and, 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 object, the Printer object MUST use the
 value of the Printer object's "job-hold-until-default" at job
 submission time (unlike most Job Template attributes that are used if
 necessary at job processing time).

4.2.3 job-sheets (type3 keyword | name(MAX))

 This attribute determines which job start/end sheet(s), if any, MUST
 be printed with a job.

deBry, et al. Experimental [Page 75] RFC 2566 IPP/1.0: Model and Semantics April 1999

 Standard keyword values are:
   'none': no job sheet is printed
   'standard': one or more site specific standard job sheets are
      printed, e.g. a single start sheet or both start and end sheet
      is printed
 An administrator MAY define additional values using the 'name' or '
 keyword' attribute syntax, depending on implementation.
 Note: The effect of this attribute on jobs with multiple documents
 MAY be affected by the "multiple-document-handling" job attribute
 (section 4.2.4), depending on the job sheet semantics.

4.2.4 multiple-document-handling (type2 keyword)

 This attribute is relevant only if a job consists of two or more
 documents. The attribute controls finishing operations and the
 placement of one or more print-stream pages into impressions and onto
 media sheets.  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
 explanations, 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(*)".
 Standard keyword values are:
   'single-document': If a Job object 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 operations; that is,
      finishing would be performed on the concatenation of the
      sequences a(*),b(*).  The Printer object MUST NOT force the data
      in each document instance to be formatted onto a new print-
      stream page, 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 object MUST force each
      copy (a(*),b(*)) to start on a new media sheet.
   'separate-documents-uncollated-copies': If a Job object 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 operations; that is, the sets a(*) and b(*) would each
      be finished separately. The Printer object 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

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      ordering of the sets of media sheets resulting from processing
      the document data MUST be a(*), a(*), ..., b(*), b(*) ... .
   'separate-documents-collated-copies': If a Job object 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
      operations; that is, the sets a(*) and b(*) would each be
      finished separately. The Printer object 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(*), ... .
   'single-document-new-sheet':  Same as 'single-document', except
      that the Printer object 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 sheet.
 The 'single-document' value is the same as 'separate-documents-
 collated-copies' with respect to ordering of print-stream pages, but
 not media sheet generation, since 'single-document' will put the
 first page of the next document on the back side of a 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 sheet.  In addition, if the "finishings"
 attribute specifies 'staple', then with 'single-document', documents
 a and b are stapled together as a single document with no regard to
 new sheets, with 'single-document-new-sheet', documents a and b are
 stapled together as a single document, but document b starts on a new
 sheet, but with 'separate-documents-uncollated-copies' and '
 separate-documents-collated-copies', documents a and b are stapled
 separately.
 Note: None of these values provide means to produce uncollated sheets
 within a document, i.e., where multiple copies of sheet n are
 produced before sheet n+1 of the same document.
 The relationship of this attribute and the other attributes that
 control document processing is described in section 15.3.

4.2.5 copies (integer(1:MAX))

 This 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 may
 be different from the number of uncollated copies which can be

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 supported.
 Note: The effect of this attribute on jobs with multiple documents is
 controlled by the "multiple-document-handling" job attribute (section
 4.2.4) and the relationship of this attribute and the other
 attributes that control document processing is described in section
 15.3.

4.2.6 finishings (1setOf type2 enum)

 This attribute identifies the finishing operations 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 are:
   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 is
                site-defined.
   '5'    'punch':  This value indicates that holes are required in
                the finished document. The exact number and placement
                of the holes is site-defined  The punch specification
                MAY be satisfied (in a site- 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 is site-defined."
 Note: The effect of this attribute on jobs with multiple documents is
 controlled by the "multiple-document-handling" job attribute (section
 4.2.4) and the relationship of this attribute and the other
 attributes that control document processing is described in section
 15.3.
 If the client supplies a value of 'none' along with any other
 combination of values, it is the same as if only that other
 combination of values had been supplied (that is the 'none' value has
 no effect).

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4.2.7 page-ranges (1setOf rangeOfInteger (1:MAX))

 This attribute identifies the range(s) of print-stream pages that the
 Printer object uses for each copy of each document which are to be
 printed.  Nothing is printed for any pages identified that do not
 exist in the document(s).  Ranges MUST be in ascending order, for
 example: 1-3, 5-7, 15-19 and MUST NOT overlap, so that a non-spooling
 Printer object can process the job in a single pass.  If the ranges
 are not ascending or are overlapping, the IPP object MUST reject the
 request and return the 'client-error-bad-request' status code.  The
 attribute is associated with print-stream pages not application-
 numbered pages (for example, 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 "copy" for purposes of the
 specified page range(s).  When "multiple-document-handling" is '
 single-document', the Printer object MUST apply each supplied page
 range once to the concatenation of the print-stream 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 object
 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 documents.
 In most cases, the exact pages to be printed will be generated by a
 device driver and this attribute would not be required.  However,
 when printing an archived document which has already been formatted,
 the end user may elect to print just a subset of the pages contained
 in the document.  In this case, if page-range = 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.
 "page-ranges-supported" is a boolean value indicating whether or not
 the printer is capable of supporting the printing of page ranges.
 This capability may 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 will be
 printed.

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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
 4.2.4) and the relationship of this attribute and the other
 attributes that control document processing is described in section
 15.3.

4.2.8 sides (type2 keyword)

 This attribute specifies how print-stream pages are to be imposed
 upon the sides of an instance of a selected medium, i.e., an
 impression.
 The standard keyword values are:
   'one-sided': imposes each consecutive print-stream page upon the
      same side of consecutive media sheets.
   'two-sided-long-edge': imposes each consecutive pair of print-
      stream pages upon front and back sides of consecutive media
      sheets, such that the orientation of each pair of print-stream
      pages 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'.
   'two-sided-short-edge': imposes each consecutive pair of print-
      stream pages upon front and back sides of consecutive media
      sheets, such that the orientation of each pair of print-stream
      pages 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'.
 'two-sided-long-edge', 'two-sided-short-edge', 'tumble', and 'duplex'
 all work the same for portrait or landscape.  However 'head-to-toe'
 is 'tumble' in portrait but 'duplex' in landscape.  'head-to-head'
 also switches between 'duplex' and 'tumble' when using portrait and
 landscape modes.
 Note: The effect of this attribute on jobs with multiple documents is
 controlled by the "multiple-document-handling" job attribute (section
 4.2.4) and the relationship of this attribute and the other
 attributes that control document processing is described in section
 15.3.

4.2.9 number-up (integer(1:MAX))

 This attribute specifies the number of print-stream pages to impose
 upon a single side of an instance of a selected medium.  For example,
 if the value is:

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   Value  Description
   '1'    the Printer MUST place one print-stream page on a single
                side of an instance of the selected medium (MAY add
                some sort of translation, scaling, or rotation).
   '2'    the Printer MUST place two print-stream pages on a single
                side of an instance of the selected medium (MAY add
                some sort of translation, scaling, or rotation).
   '4'    the Printer MUST place four print-stream pages on a single
                side of an instance of the selected medium (MAY add
                some sort of translation, scaling, or rotation).
 This attribute primarily controls the translation, scaling and
 rotation of print-stream pages.
 Note: The effect of this attribute on jobs with multiple documents is
 controlled by the "multiple-document-handling" job attribute (section
 4.2.4) and the relationship of this attribute and the other
 attributes that control document processing is described in section
 15.3.

4.2.10 orientation-requested (type2 enum)

 This attribute indicates the desired orientation for printed print-
 stream pages; it does not describe the orientation of the client-
 supplied print-stream pages.
 For some document formats (such as 'application/postscript'), the
 desired orientation of the print-stream pages is specified within the
 document data.  This information is generated by a device 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 object to bind the desired orientation to
 the document data after it has been submitted.  It is expected that a
 Printer object would only support "orientations-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 4.2, item 1, points out
 that a Printer object may support or not support any Job Template
 attribute based on the document format supplied by the client.
 However, a special mention is made here since it is very likely that
 a Printer object will support "orientation-requested" for only a
 subset of the supported document formats.

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 Standard enum values are:
   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 print-stream page to be imaged by +90
                degrees with respect to the medium (i.e. anti-
                clockwise) 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 print-stream 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 print-stream 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.
 Note: The effect of this attribute on jobs with multiple documents is
 controlled by the "multiple-document-handling" job attribute (section
 4.2.4) and the relationship of this attribute and the other
 attributes that control document processing is described in section
 15.3.

4.2.11 media (type3 keyword | name(MAX))

 This attribute identifies the medium that the Printer uses for all
 impressions of the Job.
 The values for "media" include medium-names, medium-sizes, input-
 trays and electronic forms so that one attribute specifies the media.

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 If a Printer object 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 object 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
 object 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 object 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 its prints each page.
 Standard keyword values are (taken from ISO DPA and the Printer MIB)
 and are listed in section 14. 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.
 If an IPP object supports "media-supported", it NEED NOT support
 "media-ready".
 The relationship of this attribute and the other attributes that
 control document processing is described in section 15.3.

4.2.12 printer-resolution (resolution)

 This attribute identifies the resolution that Printer uses for the
 Job.

4.2.13 print-quality (type2 enum)

 This attribute specifies the print quality that the Printer uses for
 the Job.
 The standard enum values are:
   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

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4.3 Job Description Attributes

 The attributes in this section form the attribute group called "job-
 description".  The following table summarizes these attributes.  The
 third column indicates whether the attribute is a REQUIRED attribute
 that MUST be supported by Printer objects.  If it is not indicated as
 REQUIRED, then it is OPTIONAL.  The maximum size in octets for 'text'
 and 'name' attributes is indicated in parenthesizes.
 +----------------------------+----------------------+----------------+
 |      Attribute             |     Syntax           |   REQUIRED?    |
 +----------------------------+----------------------+----------------+
 | job-uri                    | uri                  |  REQUIRED      |
 +----------------------------+----------------------+----------------+
 | job-id                     | integer(1:MAX)       |  REQUIRED      |
 +----------------------------+----------------------+----------------+
 | job-printer-uri            | uri                  |  REQUIRED      |
 +----------------------------+----------------------+----------------+
 | job-more-info              | uri                  |                |
 +----------------------------+----------------------+----------------+
 | job-name                   | name (MAX)           |  REQUIRED      |
 +----------------------------+----------------------+----------------+
 | job-originating-user-name  | name (MAX)           |  REQUIRED      |
 +----------------------------+----------------------+----------------+
 | job-state                  | type1 enum           |  REQUIRED      |
 +----------------------------+----------------------+----------------+
 | job-state-reasons          | 1setOf type2 keyword |                |
 +----------------------------+----------------------+----------------+
 | job-state-message          | text (MAX)           |                |
 +----------------------------+----------------------+----------------+
 | number-of-documents        | integer (0:MAX)      |                |
 +----------------------------+----------------------+----------------+
 | output-device-assigned     | name (127)           |                |
 +----------------------------+----------------------+----------------+
 | time-at-creation           | integer (0:MAX)      |                |
 +----------------------------+----------------------+----------------+
 | time-at-processing         | integer (0:MAX)      |                |
 +----------------------------+----------------------+----------------+
 | time-at-completed          | integer (0:MAX)      |                |
 +----------------------------+----------------------+----------------+
 | number-of-intervening-jobs | integer (0:MAX)      |                |
 +----------------------------+----------------------+----------------+
 | job-message-from-operator  | text (127)           |                |
 +----------------------------+----------------------+----------------+
 | job-k-octets               | integer (0:MAX)      |                |
 +----------------------------+----------------------+----------------+
 | job-impressions            | integer (0:MAX)      |                |
 +----------------------------+----------------------+----------------+

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 +----------------------------+----------------------+----------------+
 |      Attribute             |     Syntax           |   REQUIRED?    |
 +----------------------------+----------------------+----------------+
 | job-media-sheets           | integer (0:MAX)      |                |
 +----------------------------+----------------------+----------------+
 | job-k-octets-processed     | integer (0:MAX)      |                |
 +----------------------------+----------------------+----------------+
 | job-impressions-completed  | integer (0:MAX)      |                |
 +----------------------------+----------------------+----------------+
 | job-media-sheets-completed | integer (0:MAX)      |                |
 +----------------------------+----------------------+----------------+
 | attributes-charset         | charset              |  REQUIRED      |
 +----------------------------+----------------------+----------------+
 | attributes-natural-language| naturalLanguage      |  REQUIRED      |
 +----------------------------+----------------------+----------------+

4.3.1 job-uri (uri)

 This REQUIRED attribute contains the URI for the job.  The Printer
 object, on receipt of a new job, generates a URI which identifies the
 new Job.  The Printer object returns the value of the "job-uri"
 attribute as part of the response to a create request.  The precise
 format of a Job URI is implementation dependent.  If the Printer
 object supports more than one URI and there is some relationship
 between the newly formed Job URI and the Printer object's URI, the
 Printer object uses the Printer URI supplied by the client in the
 create request.  For example, if the create request comes in over a
 secure channel, the new Job URI MUST use the same secure channel.
 This can be guaranteed because the Printer object is responsible for
 generating the Job URI and the Printer object is aware of its
 security configuration and policy as well as the Printer URI used in
 the create request.
 For a description of this attribute and its relationship to "job-id"
 and "job-printer-uri" attribute, see the discussion in section 2.4 on
 "Object Identity".

4.3.2 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 which identifies the new Job on
 that Printer.  The Printer returns the value of the "job-id"
 attribute as part of the response to a create request.  The 0 value
 is not included to allow for compatibility with SNMP index values
 which also cannot be 0.

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 For a description of this attribute and its relationship to "job-uri"
 and "job-printer-uri" attribute, see the discussion in section 2.4 on
 "Object Identity".

4.3.3 job-printer-uri (uri)

 This REQUIRED attribute identifies the Printer object that created
 this Job object.  When a Printer object creates a Job object, it
 populates this attribute with the Printer object URI that was used in
 the create request.  This attribute permits a client to identify the
 Printer object that created this Job object when only the Job
 object's URI is available to the client.  The client queries the
 creating Printer object to determine which languages, charsets,
 operations, are supported for this Job.
 For a description of this attribute and its relationship to "job-uri"
 and "job-id" attribute, see the discussion in section 2.4 on "Object
 Identity".

4.3.4 job-more-info (uri)

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

4.3.5 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" attribute value.  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 create request (see Section 3.2.1.1).   If, however,
 the "job-name" operation attribute is not supplied by the client in
 the create request, the Printer object, 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 Content information.

4.3.6 job-originating-user-name (name(MAX))

 This REQUIRED attribute contains the name of the end user that
 submitted the print job.  The Printer object sets this attribute to
 the most authenticated printable name that it can obtain from the
 authentication service over which the IPP operation was received.

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 Only if such is not available, does the Printer object use the value
 supplied by the client in the "requesting-user-name" operation
 attribute of the create operation (see Section 8).
 Note:  The Printer object needs to keep an internal originating user
 id of some form, typically as a credential of a principal, with the
 Job object.  Since such an internal attribute is implementation-
 dependent and not of interest to clients, it is not specified as a
 Job Description attribute.  This originating user id is used for
 authorization checks (if any) on all subsequent operation.

4.3.7 job-state (type1 enum)

 This REQUIRED attribute identifies the current state of the job.
 Even though the IPP protocol defines eight values for job states,
 implementations only need to support those states which 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 object implementation.
 Standard enum values are:
   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-reason" attribute MUST
                indicate why the job is no longer a candidate for
                processing.
   '5'    'processing':  One or more of:
                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 object 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

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                device or because the job is queued in the output
                device or some other spooler, awaiting 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, though they NEED NOT,  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 IPP object is in the process of canceling or
                aborting the job.  Most implementations won't bother
                with this nuance.
   '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-reason" 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 object'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 object has completed
                canceling the job and all job status attributes have
                reached their final values for the job.  While the
                Printer object 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' value.

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                When the job moves to the 'canceled' state, the '
                processing-to-stop-point' value, if present, MUST be
                removed, but the '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 and all job status attributes have reached
                their final values for the job.  While the Printer
                object 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.
   '9'    'completed':  The job has completed successfully or with
                warnings or errors after processing and 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:  'completed-successfully', '
                completed-with-warnings', or 'completed-with-errors'
                values.
 The final value for this attribute MUST be one of: '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.
 The following figure shows the normal job state transitions.
                                                    +----> canceled
                                                   /
     +----> pending --------> processing ---------+------> completed
     |         ^                   ^               \
 --->+         |                   |                +----> aborted
     |         v                   v               /
     +----> pending-held    processing-stopped ---+
 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.

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 Jobs reach one of the three terminal states: 'completed', 'canceled',
 or 'aborted', after the jobs have completed all activity, including
 stacking output media, after the jobs have completed all activity,
 and all job status attributes have reached their final values for the
 job.
 Note: As with all other IPP attributes, if the implementation can not
 determine the correct value for this attribute, it SHOULD respond
 with the out-of-band value 'unknown' (see section 4.1) rather than
 try to guess at some possibly incorrect value and give the end user
 the wrong impression about the state of the Job object.  For example,
 if the implementation is just a gateway into some printing system
 that does not provide detailed status about the print job, the IPP
 Job object's state might literally be 'unknown'.

4.3.8 job-state-reasons (1setOf type2 keyword)

 This attribute provides additional information about the job's
 current state, i.e., information that augments the value of the job's
 "job-state" attribute.
 Implementation of these values is OPTIONAL, i.e., a Printer NEED NOT
 implement them, even if (1) the output device supports the
 functionality represented by the reason and (2) is available to the
 Printer object implementation.  These values MAY be used with any job
 state or states for which the reason makes sense.  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'.
 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), starting with the '
 job-incoming' value:
   'none':  There are no reasons for the job's current state.
   'job-incoming':  The Create-Job operation has been accepted by the
      Printer, but the Printer is expecting additional Send-Document

deBry, et al. Experimental [Page 90] RFC 2566 IPP/1.0: Model and Semantics April 1999

      and/or Send-URI operations and/or is accessing/accepting
      document data.
   '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, (3) the client crashed or failed to close the job
      before the time-out period.  See section 4.4.28.
   'job-outgoing':  The Printer is transmitting the job to the output
      device.
   '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.
   '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 printer's 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 may remain in
      its current state or be moved to the 'pending-held' state,
      depending on implementation and/or job scheduling policy.
   'printer-stopped-partly':  The value of the Printer's "printer-
      state-reasons" attribute contains the value 'stopped-partly'.
   'printer-stopped':  The value of the Printer's "printer-state"
      attribute is 'stopped'.
   'job-interpreting': Job is in the 'processing' state, but more
      specifically, the Printer is interpreting the document data.
   'job-queued': Job is in the 'processing' state, but more
      specifically, the Printer has queued the document data.
   'job-transforming': Job is in the 'processing' state, but more
      specifically, the Printer is interpreting document data and
      producing another electronic representation.
   'job-printing':  The output device is marking media. This value is
      useful for Printers which spend a great deal of time processing
      (1) when no marking is happening and then 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.
   '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 object, or by some other
      authorized end-user, such as a member of the job owner's
      security group.

deBry, et al. Experimental [Page 91] RFC 2566 IPP/1.0: Model and Semantics April 1999

   '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 may 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.
   'job-canceled-at-device':  The job was canceled by an unidentified
      local user, i.e., a user at a console at the device.
   '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.
   'processing-to-stop-point':  The requester has issued a Cancel-Job
      operation or the Printer object has aborted the job, but is
      still performing some actions on the job until a specified stop
      point occurs or job termination/cleanup is completed.
      This reason is recommended to be used in conjunction with the '
      processing' job state to indicate that the Printer object is
      still performing some actions on the job while the job remains
      in the 'processing' state.  After all the job's job description
      attributes have stopped incrementing, the Printer object moves
      the job from the 'processing' state to the 'canceled' or '
      aborted' job states.
   'service-off-line':  The Printer is off-line 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.
   'job-completed-successfully':  The job completed successfully.
   'job-completed-with-warnings':  The job completed with warnings.
   'job-completed-with-errors':  The job completed with errors (and
      possibly warnings too).

4.3.9 job-state-message (text(MAX))

 This attribute specifies information about the "job-state" and "job-
 state-reasons" attributes in human readable text.  If the Printer
 object supports this attribute, the Printer object 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 3.1.4.1).

deBry, et al. Experimental [Page 92] RFC 2566 IPP/1.0: Model and Semantics April 1999

 Note:  the value SHOULD NOT contain additional information not
 contained in the values of the "job-state" and "job-states-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, a new attribute with keyword values,
 needs to be developed and registered.

4.3.10 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 object or not.
 Implementations supporting the OPTIONAL Create-Job/Send-
 Document/Send-URI operations SHOULD support this attribute so that
 clients can query the number of documents in each job.

4.3.11 output-device-assigned (name(127))

 This attribute identifies the output device to which the Printer
 object has assigned this job.  If an output device implements an
 embedded Printer object, the Printer object NEED NOT set this
 attribute.  If a print server implements a Printer object, the value
 MAY be empty (zero-length string) or not returned until the Printer
 object assigns an output device to the job.  This attribute is
 particularly useful when a single Printer object support multiple
 devices (so called "fan-out").

4.3.12 time-at-creation (integer(0:MAX))

 This attribute indicates the point in time at which the Job object
 was created.  In order to populate this attribute, the Printer object
 uses the value in its "printer-up-time" attribute at the time the Job
 object is created.

4.3.13 time-at-processing (integer(0:MAX))

 This attribute indicates the point in time at which the Job object
 began processing.  In order to populate this attribute, the Printer
 object uses the value in its "printer-up-time" attribute at the time
 the Job object is moved into the 'processing' state for the first
 time.

deBry, et al. Experimental [Page 93] RFC 2566 IPP/1.0: Model and Semantics April 1999

4.3.14 time-at-completed (integer(0:MAX))

 This attribute indicates the point in time at which the Job object
 completed (or was cancelled or aborted).  In order to populate this
 attribute, the Printer object uses the value in its "printer-up-time"
 attribute at the time the Job object is moved into the 'completed' or
 'canceled' or 'aborted' state.

4.3.15 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.

4.3.16 job-message-from-operator (text(127))

 This attribute provides a message from an operator, system
 administrator or "intelligent" process to indicate to the end user
 the reasons for modification or other management action taken on a
 job.

4.3.17 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.
 This value MUST also 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.

deBry, et al. Experimental [Page 94] RFC 2566 IPP/1.0: Model and Semantics April 1999

 Note: This attribute and the following two attributes ("job-
 impressions" and "job-media-sheets") are not intended to be counters;
 they are intended to be useful routing and scheduling information if
 known.  For these three attributes, the Printer object may try to
 compute the value if it is not supplied in the create request.  Even
 if the client does supply a value for these three attributes in the
 create request, the Printer object MAY choose to change the value if
 the Printer object is able to compute a value which is more accurate
 than the client supplied value.  The Printer object may be able to
 determine the correct value for these three attributes either right
 at job submission time or at any later point in time.

4.3.18 job-impressions (integer(0:MAX))

 This attribute specifies the total size in number of impressions of
 the document(s) being submitted (see the definition of impression in
 section 13.2.5).
 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 MUST also 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.
 See the Note in the "job-k-octets" attribute that also applies to
 this attribute.

4.3.19 job-media-sheets (integer(0:MAX))

 This 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 system administrator to control the lower and

deBry, et al. Experimental [Page 95] RFC 2566 IPP/1.0: Model and Semantics April 1999

 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".
 See the Note in the "job-k-octets" attribute that also applies to
 this attribute.

4.3.20 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.
 Note: This attribute and the following two attributes ("job-
 impressions-completed" and "job-sheets-completed") are intended to be
 counters. That is, the value 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.

4.3.21 job-impressions-completed (integer(0:MAX))

 This job 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.
 See the note in "job-k-octets-processed" which also applies to this
 attribute.

4.3.22 job-media-sheets-completed (integer(0:MAX))

 This job attribute specifies the media-sheets completed marking and
 stacking for the entire job so far whether those sheets have been
 processed on one side or on both.
 See the note in "job-k-octets-processed" which also applies to this
 attribute.

deBry, et al. Experimental [Page 96] RFC 2566 IPP/1.0: Model and Semantics April 1999

4.3.23 attributes-charset (charset)

 This REQUIRED attribute is populated using the value in the client
 supplied "attributes-charset" attribute in the create request.  It
 identifies the charset (coded character set and encoding method) used
 by any Job attributes with attribute syntax 'text' and 'name' that
 were supplied by the client in the create request.  See Section 3.1.4
 for a complete description of the "attributes-charset" operation
 attribute.
 This attribute does not indicate the charset in which the 'text' and
 'name' values are stored internally in the Job object.  The internal
 charset is implementation-defined.  The IPP object MUST convert from
 whatever the internal charset is to that being requested in an
 operation as specified in Section 3.1.4.

4.3.24 attributes-natural-language (naturalLanguage)

 This REQUIRED attribute is populated using the value in the client
 supplied "attributes-natural-language" attribute in the create
 request.  It identifies the natural language used for any Job
 attributes with attribute syntax 'text' and 'name' that were supplied
 by the client in the create request.  See Section 3.1.4 for a
 complete description of the "attributes-natural-language" operation
 attribute.  See Sections 4.1.1.2 and 4.1.2.2 for how a Natural
 Language Override may be supplied explicitly for each 'text' and '
 name' attribute value that differs from the value identified by the
 "attributes-natural-language" attribute.

4.4 Printer Description Attributes

 These attributes form the attribute group called "printer-
 description".  The following table summarizes these attributes, their
 syntax, and whether or not they are REQUIRED for a Printer object 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 parenthesizes.
 Note: How these attributes are set by an Administrator is outside the
 scope of this specification.

deBry, et al. Experimental [Page 97] RFC 2566 IPP/1.0: Model and Semantics April 1999

+----------------------------+----------------------+----------------+
|      Attribute             |     Syntax           |   REQUIRED?    |
+----------------------------+----------------------+----------------+
| printer-uri-supported      | 1setOf uri           |  REQUIRED      |
+----------------------------+----------------------+----------------+
| uri-security-supported     | 1setOf type2 keyword |  REQUIRED      |
+----------------------------+----------------------+----------------+
| printer-name               | name (127)           |  REQUIRED      |
+----------------------------+----------------------+----------------+
| printer-location           | text (127)           |                |
+----------------------------+----------------------+----------------+
| printer-info               | text (127)           |                |
+----------------------------+----------------------+----------------+
| printer-more-info          | uri                  |                |
+----------------------------+----------------------+----------------+
| printer-driver-installer   | uri                  |                |
+----------------------------+----------------------+----------------+
| printer-make-and-model     | text (127)           |                |
+----------------------------+----------------------+----------------+
| printer-more-info-         | uri                  |                |
| manufacturer               |                      |                |
+----------------------------+----------------------+----------------+
| printer-state              | type1 enum           |  REQUIRED      |
+----------------------------+----------------------+----------------+
| printer-state-reasons      | 1setOf type2 keyword |                |
+----------------------------+----------------------+----------------+
| printer-state-message      | text (MAX)           |                |
+----------------------------+----------------------+----------------+
| operations-supported       | 1setOf type2 enum    |  REQUIRED      |
+----------------------------+----------------------+----------------+
| charset-configured         | charset              |  REQUIRED      |
+----------------------------+----------------------+----------------+
| charset-supported          | 1setOf charset       |  REQUIRED      |
+----------------------------+----------------------+----------------+
| natural-language-configured| naturalLanguage      |  REQUIRED      |
+----------------------------+----------------------+----------------+
| generated-natural-language-| 1setOf               |  REQUIRED      |
| supported                  |   naturalLanguage    |                |
+----------------------------+----------------------+----------------+
| document-format-default    | mimeMediaType        |  REQUIRED      |
+----------------------------+----------------------+----------------+
| document-format-           | 1setOf               |  REQUIRED      |
|   supported                |   mimeMediaType      |                |
+----------------------------+----------------------+----------------+
| printer-is-accepting-jobs  | boolean              |  REQUIRED      |
+----------------------------+----------------------+----------------+
| queued-job-count           | integer (0:MAX)      |  RECOMMENDED   |
+----------------------------+----------------------+----------------+

deBry, et al. Experimental [Page 98] RFC 2566 IPP/1.0: Model and Semantics April 1999

+----------------------------+----------------------+----------------+
|      Attribute             |     Syntax           |   REQUIRED?    |
+----------------------------+----------------------+----------------+
| printer-message-from-      | text (127)           |                |
| operator                   |                      |                |
+----------------------------+----------------------+----------------+
| color-supported            | boolean              |                |
+----------------------------+----------------------+----------------+
| reference-uri-schemes-     | 1setOf uriScheme     |                |
|   supported                |                      |                |
+----------------------------+----------------------+----------------+
| pdl-override-supported     | type2 keyword        |  REQUIRED      |
+----------------------------+----------------------+----------------+
| printer-up-time            | integer (1:MAX)      |  REQUIRED      |
+----------------------------+----------------------+----------------+
| printer-current-time       | dateTime             |                |
+----------------------------+----------------------+----------------+
| multiple-operation-time-out| integer (1:MAX)      |                |
+----------------------------+----------------------+----------------+
| compression-supported      | 1setOf type3 keyword |                |
+----------------------------+----------------------+----------------+
| job-k-octets-supported     | rangeOfInteger       |                |
|                            |    (0:MAX)           |                |
+----------------------------+----------------------+----------------+
| job-impressions-supported  | rangeOfInteger       |                |
|                            |    (0:MAX)           |                |
+----------------------------+----------------------+----------------+
| job-media-sheets-supported | rangeOfInteger       |                |
|                            |    (0:MAX)           |                |
+----------------------------+----------------------+----------------+

4.4.1 printer-uri-supported (1setOf uri)

 This REQUIRED Printer attribute contains at least one URI for the
 Printer object.  It OPTIONALLY contains more than one URI for the
 Printer object.    An administrator determines a Printer object's
 URI(s) and configures this attribute to contain those URIs by some
 means outside the scope of IPP/1.0.  The precise format of this URI
 is implementation dependent and depends on the protocol.  See the
 next section for a description "uri-security-supported" which is the
 REQUIRED companion attribute to this "printer-uri-supported"
 attribute.  See section 2.4 on Printer object identity and section
 8.2 on security and URIs for more information.

deBry, et al. Experimental [Page 99] RFC 2566 IPP/1.0: Model and Semantics April 1999

4.4.2 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 object via that URI. The following
 standard values are defined:
   'none': There are no secure communication channel protocols in use
      for the given URI.
   'ssl3': SSL3 [SSL] is the secure communications channel protocol in
      use for the given URI.
 Consider the following example.  For a single Printer object, an
 administrator configures the "printer-uri-supported" and "uri-
 security-supported" attributes as follows:
   "printer-uri-supported": 'http://acme.com/open-use-printer', '
      http://acme.com/restricted-use-printer', '
      http://acme.com/private-printer'
   "uri-security-supported": 'none', 'none', 'ssl3'
 In this case, one Printer object has three URIs.
  1. For the first URI, 'http://acme.com/open-use-printer', the value

'none' in "uri-security-supported" indicates that there is no

      secure channel protocol configured to run under HTTP.  The name
      implies that there is no Basic or Digest authentication being
      used, but it is up to the client to determine that while using
      HTTP underneath the IPP application protocol.
   - For the second URI, 'http://acme.com/restricted-use-printer', the
      value 'none' in "uri-security-supported" indicates that there is
      no secure channel protocol configured to run under HTTP.  In
      this case, although the name does imply that there is some sort
      of Basic or Digest authentication being used within HTTP, it is
      up to the client to determine that while using HTTP and by
      processing any '401 Unauthorized' HTTP error messages.
   - For the third URI, 'http://acme.com/private-printer', the value '
      ssl3' in "uri-security-supported" indicates that SSL3 is being
      used to secure the channel.  The client SHOULD be prepared to
      use SSL3 framing to negotiate an acceptable ciphersuite to use
      while communicating with the Printer object.  In this case, the
      name implies the use of a secure communications channel, but the
      fact is made explicit by the presence of the 'ssl3' value in

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      "uri-security-supported".  The client does not need to resort to
      understanding which security it must use by following naming
      conventions or by parsing the URI to determine which security
      mechanisms are implied.
 It is expected that many IPP Printer objects will be configured to
 support only one channel (either configured to use SSL3 access or
 not), and will therefore only ever have one URI listed in the
 "printer-uri-supported" attribute.  No matter the configuration of
 the Printer object (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.

4.4.3 printer-name (name(127))

 This REQUIRED Printer attribute contains the name of the Printer
 object.  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 may be the last part of the printer's URI or it
 may be unrelated.  In non-US-English locales, a name may contain
 characters that are not allowed in a URI.

4.4.4 printer-location (text(127))

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

4.4.5 printer-info (text(127))

 This Printer attribute identifies the descriptive information about
 this Printer object.  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,
 1997, please find a new printer".

4.4.6 printer-more-info (uri)

 This Printer attribute contains a URI used to obtain more information
 about this specific Printer object.  For example, this could be an
 HTTP type 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, end user assistance). The device manufacturer may initially
 populate this attribute.

deBry, et al. Experimental [Page 101] RFC 2566 IPP/1.0: Model and Semantics April 1999

4.4.7 printer-driver-installer (uri)

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

4.4.8 printer-make-and-model (text(127))

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

4.4.9 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, print
 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
 may initially populate this attribute.

4.4.10 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 object need only update this attribute before responding to
 an operation which requests the attribute; the Printer object NEED
 NOT update this attribute continually, since asynchronous event
 notification is not part of IPP/1.0.  A Printer NEED NOT implement
 all values if they are not applicable to a given implementation.
 The following standard enum values are defined:
   Value  Symbolic Name and Description
   '3'    'idle':  If a Printer receives a job (whose required
                resources are ready) while in this state, such a job
                MUST transit into the 'processing' state immediately.
                If the "printer-state-reasons" attribute contains any
                reasons, they MUST be reasons that would not prevent a
                job from transiting into the 'processing' state
                immediately, e.g., 'toner-low'. Note: if a Printer

deBry, et al. Experimental [Page 102] RFC 2566 IPP/1.0: Model and Semantics April 1999

                controls more than one output device, the above
                definition implies that a Printer is 'idle' if at
                least one output device is idle.
   '4'    'processing':  If a Printer receives a job (whose required
                resources are ready) while in this state, such a job
                MUST transit into the 'pending' state immediately.
                Such a job MUST transit into the 'processing' state
                only after jobs ahead of it complete.  If the
                "printer-state-reasons" attribute contains any
                reasons, they MUST be reasons that do not prevent the
                current job from printing, e.g.  'toner-low'.  Note:
                if a Printer controls more than one output device, the
                above definition implies that a Printer is '
                processing' if at least one output device is
                processing, and none is idle.
   '5'    'stopped':  If a Printer receives a job (whose required
                resources are ready) while in this state, such a job
                MUST transit into the 'pending' state immediately.
                Such a job MUST transit into the 'processing' state
                only after some human fixes the problem that stopped
                the printer and after jobs ahead of it complete
                processing.  If supported, the "printer-state-reasons"
                attribute MUST contain at least one reason, e.g. '
                media-jam', which prevents it from either processing
                the current job or transitioning a 'pending' job to
                the 'processing' state.
                Note: if a Printer controls more than one output
                device, the above definition implies that a Printer is
                'stopped' only if all output devices are stopped.
                Also, it is tempting to define 'stopped' as when a
                sufficient number of output devices are stopped and
                leave it to an implementation to define the sufficient
                number.  But such a rule complicates the definition of
                'stopped' and 'processing'. For example, with this
                alternate definition of 'stopped', a job can move from
                'pending' to 'processing' without human intervention,
                even though the Printer is stopped.

4.4.11 printer-state-reasons (1setOf type2 keyword)

 This Printer attribute supplies additional detail about the device's
 state.

deBry, et al. Experimental [Page 103] RFC 2566 IPP/1.0: Model and Semantics April 1999

 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).
  1. '-report': This suffix indicates that the reason is a "report".

An implementation may 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.
   - '-warning': This suffix indicates that the reason is a "warning".
      An implementation may 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 may be of lower quality.
   - '-error': This suffix indicates that the reason is an "error".
      An implementation MUST include all errors. If this attribute
      contains one or more errors, printer MUST be in the stopped
      state.
 If the implementation does not add any one of the three suffixes, all
 parties MUST assume that the reason is an "error".
 If a Printer object 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 object as a
 whole MAY appear as a warning in the Printer's "printer-state-reasons
 attribute".  If the "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:
   'other': The device has detected an error other than one listed in
      this document.
   'none': There are not reasons. This state reason is semantically
      equivalent to "printer-state-reasons" without any value.
   'media-needed': A tray has run out of media.
   'media-jam': The device has a media jam.
   'paused': Someone has paused the Printer object.  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.
   'shutdown': Someone has removed a Printer object from service, and
      the device may be powered down or physically removed.  In this
      state, a Printer object MUST NOT produce printed output, and
      unless the Printer object is realized by a print server that is

deBry, et al. Experimental [Page 104] RFC 2566 IPP/1.0: Model and Semantics April 1999

      still active, the Printer object MUST perform no other
      operations requested by a client, including returning this
      value. If a Printer object had been printing a job when it was
      shutdown, the Printer NEED NOT resume printing that job when the
      Printer is no longer shutdown. If the Printer resumes printing
      such a job, it may leave evidence in the printed output of such
      a shutdown, e.g. the part printed before the shutdown may be
      printed a second time after the shutdown.
   'connecting-to-device': The Printer object 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).
   '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.
   'stopping': The Printer object is in the process of stopping the
      device and will be stopped in a while. When the device is
      stopped, the Printer object will change the Printer object'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.
   'stopped-partly': When a Printer object 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.
   'toner-low': The device is low on toner.
   'toner-empty': The device is out of toner.
   'spool-area-full': The limit of persistent storage allocated for
      spooling has been reached.
   'cover-open': One or more covers on the device are open.
   'interlock-open': One or more interlock devices on the printer are
      unlocked.
   'door-open': One or more doors on the device are open.
   'input-tray-missing': One or more input trays are not in the
      device.
   'media-low': At least one input tray is low on media.
   'media-empty': At least one input tray is empty.
   'output-tray-missing': One or more output trays are not in the
      device
   'output-area-almost-full': One or more output area is almost full
      (e.g. tray, stacker, collator).
   'output-area-full': One or more output area is full. (e.g. tray,
      stacker, collator)
   'marker-supply-low': The device is low on at least one marker
      supply.  (e.g. toner, ink, ribbon)

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   'marker-supply-empty: The device is out of at least one marker
      supply. (e.g. toner, ink, ribbon)
   'marker-waste-almost-full': The device marker supply waste
      receptacle is almost full.
   'marker-waste-full': The device marker supply waste receptacle is
      full.
   'fuser-over-temp': The fuser temperature is above normal.
   'fuser-under-temp': The fuser temperature is below normal.
   'opc-near-eol': The optical photo conductor is near end of life.
   'opc-life-over': The optical photo conductor is no longer
      functioning.
   'developer-low': The device is low on developer.
   'developer-empty: The device is out of developer.
   'interpreter-resource-unavailable': An interpreter resource is
      unavailable (i.e. font, form)

4.4.12 printer-state-message (text(MAX))

 This Printer attribute specifies the additional information about the
 printer state and printer state reasons in human readable text.  If
 the Printer object supports this attribute, the Printer object 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 3.1.4.1).

4.4.13 operations-supported (1setOf type2 enum)

 This REQUIRED Printer attribute specifies the set of supported
 operations for this Printer object and contained Job objects.  All
 32-bit enum values for this attribute MUST NOT exceed 0x8FFF, since
 these values are passed in two octets in each Protocol request
 [RFC2565].
 The following standard enum and "operation-id" (see section 3.1.2)
 values are defined:
   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

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   0x0008              Cancel-Job
   0x0009              Get-Job-Attributes
   0x000A              Get-Jobs
   0x000B              Get-Printer-Attributes
   0x000C-0x3FFF       reserved for future operations
   0x4000-0x8FFF       reserved for private extensions
 This allows for certain vendors to implement private extensions that
 are guaranteed to not conflict with future registered extensions.
 However, there is no guarantee that two or more private extensions
 will not conflict.

4.4.14 charset-configured (charset)

 This REQUIRED Printer attribute identifies the charset that the
 Printer object has been configured to represent 'text' and 'name'
 Printer attributes that are set by the operator, system
 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 object's
 "charset-configured" attribute MUST also be among the values of the
 Printer object's "charset-supported" attribute.

4.4.15 charset-supported (1setOf charset)

 This REQUIRED Printer attribute identifies the set of charsets that
 the Printer and contained Job objects support in attributes with
 attribute syntax 'text' and 'name'. At least the value 'utf-8' MUST
 be present, since IPP objects MUST support the UTF-8 [RFC2279]
 charset.  If a Printer object supports a charset, it means that for
 all attributes of syntax 'text' and 'name' the IPP object MUST (1)
 accept the charset in requests and return the charset in responses as
 needed.
 If more charsets than UTF-8 are supported, the IPP object MUST
 perform charset conversion between the charsets as described in
 Section 3.2.1.2.

4.4.16 natural-language-configured (naturalLanguage)

 This REQUIRED Printer attribute identifies the natural language that
 the Printer object has been configured to represent 'text' and 'name'
 Printer attributes that are set by the operator, system
 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 object MAY return them in the configured natural language
 specified by this attribute, instead of the natural language

deBry, et al. Experimental [Page 107] RFC 2566 IPP/1.0: Model and Semantics April 1999

 requested by the client in the "attributes-natural-language"
 operation attribute.  See Section 3.1.4.1 for the specification of
 the OPTIONAL multiple natural language support.  Therefore, the value
 of the Printer object's "natural-language-configured" attribute MUST
 also be among the values of the Printer object's "generated-natural-
 language-supported" attribute.

4.4.17 generated-natural-language-supported (1setOf naturalLanguage)

 This REQUIRED Printer attribute identifies the natural language(s)
 that the Printer object and contained Job objects support in
 attributes with attribute syntax 'text' and 'name'.  The natural
 language(s) supported depends on implementation and/or configuration.
 Unlike charsets, IPP objects MUST accept requests with any natural
 language or any Natural Language Override whether the natural
 language is supported or not.
 If a Printer object supports a natural language, it means that for
 any of the attributes for which the Printer or Job object generates
 messages, i.e., for the "job-state-message" and "printer-state-
 message" attributes and Operation Messages (see Section 3.1.5) in
 operation responses, the Printer and Job objects MUST be able to
 generate messages in any of the Printer's supported natural
 languages.  See section 3.1.4 for the specification of 'text' and '
 name' attributes in operation requests and responses.
 Note: A Printer object that supports multiple natural languages,
 often has separate catalogs of messages, one for each natural
 language supported.

4.4.18 document-format-default (mimeMediaType)

 This REQUIRED Printer attribute identifies the document format that
 the Printer object 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
 types).  For further details see the description of the '
 mimeMediaType' attribute syntax in Section 4.1.9.

4.4.19 document-format-supported (1setOf mimeMediaType)

 This REQUIRED Printer attribute identifies the set of document
 formats that the Printer object and contained Job objects can
 support. For further details see the description of the '
 mimeMediaType' attribute syntax in Section 4.1.9.

4.4.20 printer-is-accepting-jobs (boolean)

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 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 object is
 currently rejecting any jobs submitted to it.  In this case, the
 Printer object returns the 'server-error-not-accepting-jobs' status
 code.
 Note: 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 may cause
 the Printer to reject jobs when the "printer-state" is 'idle' or it
 may cause the Printer object to accepts jobs when the "printer-state"
 is 'stopped'.

4.4.21 queued-job-count (integer(0:MAX))

 This RECOMMENDED 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 object.

4.4.22 printer-message-from-operator (text(127))

 This Printer attribute provides a message from an operator, system
 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.

4.4.23 color-supported (boolean)

 This 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 (none are external IPP attributes in IPP/1.0).
 Note:  end-users are able to determine the nature and details of the
 color support by querying the "printer-more-info-manufacturer"
 Printer attribute.

4.4.24 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 operation.  If a Printer object supports these optional
 operations, it MUST support the "reference-uri-schemes-supported"
 Printer attribute with at least the following schemed URI value:
   'ftp':  The Printer object will use an FTP 'get' operation as

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      defined in RFC 2228 [RFC2228] using FTP URLs as defined by
      [RFC2396] and[RFC2316].
 The Printer object MAY OPTIONALLY support other URI schemes (see
 section 4.1.6).

4.4.25 pdl-override-supported (type2 keyword)

 This REQUIRED Printer attribute expresses the ability for a
 particular Printer implementation to either attempt to override
 document data instructions with IPP attributes or not.
 This attribute takes on the following values:
  1. 'attempted': This value indicates that the Printer object

attempts to make the IPP attribute values take precedence over

     embedded instructions in the document data, however there is no
     guarantee.
  1. 'not-attempted': This value indicates that the Printer object

makes no attempt to make the IPP attribute values take precedence

     over embedded instructions in the document data.
 Section 15 contains a full description of how this attribute
 interacts with and affects other IPP attributes, especially the
 "ipp-attribute-fidelity" attribute.

4.4.26 printer-up-time (integer(1:MAX))

 This REQUIRED Printer attribute indicates the amount of time (in
 seconds) that this instance of this Printer implementation has been
 up and running.  This value is used to populate the Job attributes
 "time-at-creation", "time-at-processing", and "time-at-completed".
 These time values are all measured in seconds and all have meaning
 only relative to this attribute, "printer-up-time".  The value is a
 monotonically increasing value starting from 1 when the Printer
 object is started-up (initialized, booted, etc.).
 If the Printer object 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 the first case, the Printer SHOULD not tweak any existing related
 Job attributes ("time-at-creation", "time-at-processing", and "time-
 at-completed").  In the second case, the Printer object SHOULD reset

deBry, et al. Experimental [Page 110] RFC 2566 IPP/1.0: Model and Semantics April 1999

 those attributes to 0.  If a client queries a time-related Job
 attribute and finds the value to be 0, the client MUST assume that
 the Job was submitted in some life other than the Printer's current
 life.

4.4.27 printer-current-time (dateTime)

 This Printer attribute indicates the current absolute wall-clock
 time.  If an implementation supports this attribute, then a client
 could calculate the absolute wall-clock time each Job's "time-at-
 creation", "time-at-processing", and "time-at-completed" attributes
 by using both "printer-up-time" and this attribute, "printer-
 current-time".  If an implementation does not support this attribute,
 a client can only calculate the relative time of certain events based
 on the REQUIRED "printer-up-time" attribute.

4.4.28 multiple-operation-time-out (integer(1:MAX))

 This Printer attributes identifies the minimum time (in seconds) that
 the Printer object waits for additional Send-Document or Send-URI
 operations to follow a still-open multi-document Job object before
 taking  any recovery actions, such as the ones indicated in section
 3.3.1.
 It is RECOMMENDED that vendors supply a value for this attribute that
 is between 60 and 240 seconds.  An implementation MAY allow a system
 administrator to set this attribute.  If so, the system administrator
 MAY be able to set values outside this range.

4.4.29 compression-supported (1setOf type3 keyword)

 This 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,
 Send-Document, and Send-URI requests.
 Standard values are :
   'none': no compression is used.
   'deflate':  ZIP public domain inflate/deflate) compression
      technology
   'gzip' GNU zip compression technology described in RFC 1952
      [RFC1952].
   'compress': UNIX compression technology

4.4.30 job-k-octets-supported (rangeOfInteger(0:MAX))

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 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 attributes in create requests.  The corresponding
 job description attribute "job-k-octets" is defined in section
 4.3.17.
 4.4.31 job-impressions-supported (rangeOfInteger(0:MAX))
 This 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 attributes
 in create requests.  The corresponding job description attribute
 "job-impressions" is defined in section 4.3.18.

4.4.32 job-media-sheets-supported (rangeOfInteger(0: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 attributes
 in create requests.  The corresponding Job attribute "job-media-
 sheets" is defined in section 4.3.19.

5. Conformance

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

5.1 Client Conformance Requirements

 A conforming client MUST support 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 of the Model document as
 specified in Sections 3 and 4.  A conforming client MAY supply any
 registered extensions and/or private extensions in an operation
 request, as long as they meet the requirements in Section 6.
 Otherwise, there are no conformance requirements placed on the user
 interfaces provided by IPP clients or their applications.  For
 example, one application might not allow an end user to submit
 multiple documents per job, while another does.  One application
 might first query a Printer object in order to supply a graphical
 user interface (GUI) dialogue box with supported and default values
 whereas a different implementation might not.

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 When sending a request, an IPP client NEED NOT supply any attributes
 that are indicated as OPTIONALLY supplied by the client.
 A client MUST be able to accept any of the attribute syntaxes defined
 in Section 4.1, including their full range, that may be returned to
 it in a response from a Printer object.  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 query response may contain attribute groups, attributes, and values
 that the client does not expect.  Therefore, a client implementation
 MUST gracefully handle such responses and not refuse to inter-operate
 with a conforming Printer that is returning extended registered or
 private attributes and/or attribute values that conform to Section 6.
 Clients may choose to ignore any parameters, attributes, or values
 that they do not understand.

5.2 IPP Object Conformance Requirements

 This section specifies the conformance requirements for conforming
 implementations with respect to objects, operations, and attributes.

5.2.1 Objects

 Conforming implementations MUST implement all of the model objects as
 defined in this specification in the indicated sections:
   Section 2.1 - Printer Object
   Section 2.2 - Job Object

5.2.2 Operations

 Conforming IPP object implementations MUST implement all of the
 REQUIRED model operations, including REQUIRED responses, as defined
 in this specification in the indicated sections:
   For a Printer object:
      Print-Job (section 3.2.1)          REQUIRED
      Print-URI (section 3.2.2)          OPTIONAL
      Validate-Job (section 3.2.3)       REQUIRED
      Create-Job (section 3.2.4)         OPTIONAL

deBry, et al. Experimental [Page 113] RFC 2566 IPP/1.0: Model and Semantics April 1999

      Get-Printer-Attributes (section 3.2.5)  REQUIRED
      Get-Jobs (section 3.2.6)           REQUIRED
   For a Job object:
      Send-Document (section 3.3.1)      OPTIONAL
      Send-URI (section 3.3.2)           OPTIONAL
      Cancel-Job (section 3.3.3)         REQUIRED
      Get-Job-Attributes (section 3.3.4) REQUIRED
 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 attribute groups received in a
 request, but MUST reject a request that contains a supported
 operation attribute that contains an unsupported value.
 The following section on object attributes specifies the support
 required for object attributes.

5.2.3 IPP Object Attributes

 Conforming IPP objects MUST support all of the REQUIRED object
 attributes, as defined in this specification 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 5.2.4. 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.

5.2.4 Extensions

 A conforming IPP object MAY support registered extensions and private
 extensions, as long as they meet the requirements specified in
 Section 6.
 For each attribute included in an operation response, a conforming
 IPP object MUST return a value whose type and value syntax conforms
 to the requirement of the Model document as specified in Sections 3
 and 4.

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5.2.5 Attribute Syntaxes

 An IPP object MUST be able to accept any of the attribute syntaxes
 defined in Section 4.1, including their full range, in any operation
 in which a client may supply attributes or the system administrator
 may configure attributes (by means outside the scope of IPP/1.0).  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 syntax specified in Section
 4.1, including their full range if supplied previously by a client.

5.3 Charset and Natural Language Requirements

 All clients and IPP objects MUST support the 'utf-8' charset as
 defined in section 4.1.7.
 IPP objects MUST be able to accept any client request which 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
 3.1.4).  That is, the IPP object that supports a natural language
 NEED NOT be a general purpose translator of any arbitrary 'text' or '
 name' value supplied by the client into that natural language.
 However, the object MUST be able to translate (automatically
 generate) any of its own attribute values and messages into that
 natural language.

5.4 Security Conformance Requirements

 Conforming IPP Printer objects MAY support Secure Socket Layer
 Version 3 (SSL3) [SSL] access, support access without SSL3 or support
 both means of access.
 Conforming IPP clients SHOULD support SSL3 access and non-SSL3
 access.  Note: This client requirement to support both means that
 conforming IPP clients will be able to inter-operate with any IPP
 Printer object.

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 For a detailed discussion of security considerations and the IPP
 application security profile required for SSL3 support, see section
 8.

6. IANA Considerations (registered and private extensions)

 This section describes how IPP can be extended to allow the following
 registered and private extensions to IPP:
   1. keyword attribute values
   2. enum attribute values
   3. attributes
   4. attribute syntaxes
   5. operations
   6. attribute groups
   7. status codes
 Extensions registered for use with IPP/1.0 are OPTIONAL for client
 and IPP object conformance to the IPP/1.0 Model specification.
 These extension procedures are aligned with the guidelines as set
 forth by the IESG [RFC2434].  Section 11 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 Section 11.  IPP/1.0 may also be
 extended by an appropriate RFC that specifies any of the above
 extensions.

6.1 Typed 'keyword' and 'enum' Extensions

 IPP allows for 'keyword' and 'enum' extensions (see sections 4.1.2.3
 and 4.1.4).  This document uses prefixes to the 'keyword' and 'enum'
 basic attribute syntax type in order to communicate extra information
 to the reader through its name. This extra information is not
 represented in the protocol because it is unimportant to a client or
 Printer object.  The list below describes the prefixes and their
 meaning.
   "type1":  The IPP specification must be revised to add a new
      keyword or a new enum.  No private keywords or enums are
      allowed.
   "type2":  Implementers can, at any time, add new keyword or enum
      values by proposing the complete specification to IANA:
      iana@iana.org

deBry, et al. Experimental [Page 116] RFC 2566 IPP/1.0: Model and Semantics April 1999

      IANA will forward the registration proposal to the IPP
      Designated Expert who will review the proposal with a mailing
      list that the Designated Expert keeps for this purpose.
      Initially, that list will be the mailing list used by the IPP
      WG:
           ipp@pwg.org
      even after the IPP WG is disbanded as permitted by [RFC2434].
      The IPP Designated Expert is appointed by the IESG Area Director
      responsible for IPP, according to [RFC2434].
      When a type2 keyword or enum is approved, the IPP Designated
      Expert becomes the point of contact for any future maintenance
      that might be required for that registration.
   "type3":  Implementers can, at any time, add new keyword and enum
      values by submitting the complete specification to IANA as for
      type2 who will forward the proposal to the IPP Designated
      Expert.  While no additional technical review is required, the
      IPP Designated Expert may, at his/her discretion, forward the
      proposal to the same mailing list as for type2 registrations for
      advice and comment.
      When a type3 keyword or enum is approved by the IPP Designated
      Expert, the original proposer becomes the point of contact for
      any future maintenance that might be required for that
      registration.
 For type2 and type3 keywords, the proposer includes the name of the
 keyword in the registration proposal and the name is part of the
 technical review.
 After type2 and type3 enums specifications are approved, the IPP
 Designated Expert in consultation with IANA assigns the next
 available enum number for each enum value.
 IANA will publish approved type2 and type3 keyword and enum
 attributes value registration specifications in:
      ftp.isi.edu/iana/assignments/ipp/attribute-values/xxx/yyy.txt
 where xxx is the attribute name that specifies the initial values and
 yyy.txt is a descriptive file name that contains one or more enums or
 keywords approved at the same time.  For example, if several
 additional enums for stapling are approved for use with the

deBry, et al. Experimental [Page 117] RFC 2566 IPP/1.0: Model and Semantics April 1999

 "finishings" attribute (and "finishings-default" and "finishings-
 supported" attributes), IANA will publish the additional values in
 the file:
      ftp.isi.edu/iana/assignments/ipp/attribute-
      values/finishings/stapling.txt
 Note: Some attributes are defined to be: 'type3 keywords' | 'name'
 which allows for attribute values to be extended by a site
 administrator with administrator defined names.  Such names are not
 registered with IANA.
 By definition, each of the three types above assert some sort of
 registry or review process in order for extensions to be considered
 valid.  Each higher numbered level (1, 2, 3) tends to be decreasingly
 less stringent than the previous level.   Therefore, any typeN value
 MAY be registered using a process for some typeM where M is less than
 N, however such registration is NOT REQUIRED.  For example, a type3
 value MAY be registered in a type 1 manner (by being included in a
 future version of an IPP specification), however, it is NOT REQUIRED.
 This specification defines keyword and enum values for all of the
 above types, including type3 keywords.
 For private (unregistered) keyword extensions, implementers SHOULD
 use keywords with a suitable distinguishing prefix, such as "xxx-"
 where xxx is the (lowercase) fully qualified company name registered
 with IANA for use in domain names [RFC1035].  For example, if the
 company XYZ Corp.  had obtained the domain name "XYZ.com", then a
 private keyword 'abc' would be: 'xyz.com-abc'.
 Note: RFC 1035 [RFC1035] indicates that while upper and lower case
 letters are allowed in domain names, no significance is attached to
 the case.  That is, two names with the same spelling but different
 case are to be treated as if identical.  Also, the labels in a domain
 name must follow the rules for ARPANET host names:  They must start
 with a letter, end with a letter or digit, and have as interior
 characters only letters, digits, and hyphen.  Labels must be 63
 characters or less.  Labels are separated by the "." character.
 For private (unregistered) enum extension, implementers MUST use
 values in the reserved integer range which is 2**30 to 2**31-1.

deBry, et al. Experimental [Page 118] RFC 2566 IPP/1.0: Model and Semantics April 1999

6.2 Attribute Extensibility

 Attribute names are type2 keywords.  Therefore, new attributes may be
 registered and have the same status as attributes in this document by
 following the type2 extension rules.  For private (unregistered)
 attribute extensions, implementers SHOULD use keywords with a
 suitable distinguishing prefix as described in Section 6.1.
 IANA will publish approved attribute registration specifications as
 separate files:
      ftp.isi.edu/iana/assignments/ipp/attributes/xxx-yyy.txt
 where "xxx-yyy" is the new attribute name.
 If a new Printer object 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 3.2.5.1)."
 If the specification does not, then its value in the Get-Printer-
 Attributes response MUST NOT depend on the "document-format" supplied
 in the request.  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.

6.3 Attribute Syntax Extensibility

 Attribute syntaxes are like type2 enums.  Therefore, new attribute
 syntaxes may be registered and have the same status as attribute
 syntaxes in this document by following the type2 extension rules
 described in Section 6.1.  The value codes that identify each of the
 attribute syntaxes are assigned in the Encoding and Transport
 specification [RFC2565], including a designated range for private,
 experimental use.
 For attribute syntaxes, the IPP Designated Expert in consultation
 with IANA assigns the next attribute syntax code in the appropriate
 range as specified in [RFC2565].  IANA will publish approved
 attribute syntax registration specifications as separate files:
      ftp.isi.edu/iana/assignments/ipp/attribute-syntaxes/xxx-yyy.txt
 where 'xxx-yyy' is the new attribute syntax name.

deBry, et al. Experimental [Page 119] RFC 2566 IPP/1.0: Model and Semantics April 1999

6.4 Operation Extensibility

 Operations may also be registered following the type2 procedures
 described in Section 6.1, though major new operations will usually be
 done by a new standards track RFC that augments this document.  For
 private (unregistered) operation extensions, implementers MUST use
 the range for the "operation-id" in requests specified in Section
 4.4.13 "operations-supported" Printer attribute.
 For operations, the IPP Designated Expert in consultation with IANA
 assigns the next operation-id code as specified in Section 4.4.13.
 IANA will publish approved operation registration specifications as
 separate files:
      ftp.isi.edu/iana/assignments/ipp/operations/Xxx-Yyy.txt
 where "Xxx-Yyy" is the new operation name.

6.5 Attribute Groups

 Attribute groups passed in requests and responses may be registered
 following the type2 procedures described in Section 6.1.  The tags
 that identify each of the attribute groups are assigned in [RFC2565].
 For attribute groups, the IPP Designated Expert in consultation with
 IANA assigns the next attribute group tag code in the appropriate
 range as specified in [RFC2565].  IANA will publish approved
 attribute group registration specifications as separate files:
      ftp.isi.edu/iana/assignments/ipp/attribute-group-tags/xxx-yyy-
      tag.txt
 where 'xxx-yyy-tag' is the new attribute group tag name.

6.6 Status Code Extensibility

 Operation status codes may also be registered following the type2
 procedures described in Section 6.1.  The values for status codes are
 allocated in ranges as specified in Section 13 for each status code
 class:
   "informational" - Request received, continuing process
   "successful" - The action was successfully received, understood,
      and accepted
   "redirection" - Further action must be taken in order to complete
      the request
   "client-error" - The request contains bad syntax or cannot be
      fulfilled

deBry, et al. Experimental [Page 120] RFC 2566 IPP/1.0: Model and Semantics April 1999

   "server-error" - The IPP object  failed to fulfill an apparently
      valid request
 For private (unregistered) operation status code extensions,
 implementers MUST use the top of each range as specified in Section
 13.
 For operation status codes, the IPP Designated Expert in consultation
 with IANA assigns the next status code in the appropriate class range
 as specified in Section 13.  IANA will publish approved status code
 registration specifications as separate files:
      ftp.isi.edu/iana/assignments/ipp/status-codes/xxx-yyy.txt
 where "xxx-yyy" is the new operation status code keyword.

6.7 Registration of MIME types/sub-types for document-formats

 The "document-format" attribute's syntax is 'mimeMediaType'.  This
 means that valid values are Internet Media Types (see Section 4.1.9).
 RFC 2045 [RFC2045] defines the syntax for valid Internet media types.
 IANA is the registry for all Internet media types.

6.8 Registration of charsets for use in 'charset' attribute values

 The "attributes-charset" attribute's syntax is 'charset'.  This means
 that valid values are charsets names.  When a charset in the IANA
 registry has more than one name (alias), the name labeled as
 "(preferred MIME name)", if present, MUST be used (see Section
 4.1.7).  IANA is the registry for charsets following the procedures
 of [RFC2278].

7. Internationalization Considerations

 Some of the attributes have values that are text strings and names
 which are intended for human understanding rather than machine
 understanding (see the 'text' and 'name' attribute syntaxes in
 Sections 4.1.1 and 4.1.2).
 In each operation request, the client
  1. identifies the charset and natural language of the request which

affects each supplied 'text' and 'name' attribute value, and

  1. requests the charset and natural language for attributes returned

by the IPP object in operation responses (as described in Section

     3.1.4.1).

deBry, et al. Experimental [Page 121] RFC 2566 IPP/1.0: Model and Semantics April 1999

 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' technique
 described section 4.1.1.2 and 4.1.2.2 respectively.
 All IPP objects MUST support the UTF-8 [RFC2279] 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 3.1.4.2.  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 3.1.4.1).
 For Printers that support multiple charsets and/or multiple natural
 languages in 'text' and 'name' attributes, different jobs may 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' mechanism to identify the differing natural
 languages with each job attribute returned.
 The Printer object also has configured charset and natural language
 attributes.   The client can query the Printer object to determine
 the list of charsets and natural languages supported by the Printer
 object and what the Printer object's configured values are.  See the
 "charset-configured", "charset-supported", "natural-language-
 configured", and "generated-natural-language-supported" Printer
 description attributes for more details.
 The "charset-supported" attributed 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 which 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.  Just because a Printer object is currently

deBry, et al. Experimental [Page 122] RFC 2566 IPP/1.0: Model and Semantics April 1999

 configured to support 'en-us' natural language does not mean that the
 Printer object should reject a job if the client supplies a job name
 that is in 'fr-ca'.
 The "natural-language-configured" attribute identifies the one
 supported natural language for generated messages which is the native
 natural language given the current configuration of the IPP object
 (administrator defined).
 Attributes of type 'text' and 'name' are populated from different
 sources.  These attributes can be categorized into 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 object'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 system administrator (e.g.,
      the Printer object's "printer-name" and "printer-location"
      attributes).  These too can 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.
   3. Some attributes are supplied by the device manufacturer (e.g.,
      the Printer object's "printer-make-and-model" attribute).  These
      too can 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
      object's "job-message-from-operator" attribute). These too can
      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
      object's "job-state-message" attribute, the Printer object'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).

deBry, et al. Experimental [Page 123] RFC 2566 IPP/1.0: Model and Semantics April 1999

 The 'text' and 'name' attributes specified in this version of this
 document (additional ones will be registered according to the
 procedures in Section 6) are:
   Attributes                      Source
   --------------------------      ----------
   Operation Attributes
      job-name (name)               client
      document-name (name)          client
      requesting-user-name (name)   client
      status-message                Job or Printer object
   Job Template Attributes:
      job-hold-until)          client matches administrator-configured
          (keyword | name
      job-hold-until-default   client matches administrator-configured
          (keyword | name)
      job-hold-until-supported client matches administrator-configured
          (keyword | name)
      job-sheets               client matches administrator-configured
          (keyword | name)
      job-sheets-default       client matches administrator-configured
          (keyword | name)
      job-sheets-supported     client matches administrator-configured
          (keyword | name)
      media                    client matches administrator-configured
          (keyword | name)
      media-default            client matches administrator-configured
          (keyword | name)
      media-supported          client matches administrator-configured
          (keyword | name)
      media-ready              client matches administrator-configured
          (keyword | name)
   Job Description Attributes:
      job-name (name)               client or Printer object
      job-originating-user-name (name)   Printer object
      job-state-message (text)      Job or Printer object
      output-device-assigned (name(127)) administrator
      job-message-from-operator (text(127))   operator
   Printer Description Attributes:
      printer-name (name(127))      administrator
      printer-location (text(127))  administrator
      printer-info (text(127))      administrator
      printer-make-and-model (text(127)) administrator or manufacturer
      printer-state-message (text)  Printer object
      printer-message-from-operator (text(127))    operator

deBry, et al. Experimental [Page 124] RFC 2566 IPP/1.0: Model and Semantics April 1999

8. Security Considerations

 Some IPP objects MAY be deployed over protocol stacks that support
 Secure Socket Layer Version 3 (SSL3) [SSL].  Note:  SSL3 is not an
 IETF standards track specification.  Other IPP objects MAY be
 deployed over protocol stacks that do not support SSL3.  Some IPP
 objects MAY be deployed over both types of protocol stacks.  Those
 IPP objects that support SSL3, are capable of supporting mutual
 authentication as well as privacy of messages via multiple encryption
 schemes.  An important point about security related information for
 SSL3 access to an IPP object, is that the security-related parameters
 (authentication, encryption keys, etc.) are "out-of-band" to the
 actual IPP protocol.
 An IPP object that does not support SSL3 MAY elect to support a
 transport layer that provides other security mechanisms.  For
 example, in a mapping of IPP over HTTP/1.1 [RFC2565], if the IPP
 object does not support SSL3, HTTP still allows for client
 authentication using Digest Access Authentication (DAA) [RFC2069].
 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
 corporation over a private network, the risks of exposing document
 data may be low enough that the corporation 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 may
 wish to protect the content of the information during transmission
 through the network with encryption.
 Furthermore, the value of the information being printed may 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 possibly of denial-of-
 service attacks, but denial-of-service attacks against printing
 resources are not well understood and there is 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 IPP/1.0, and must be established via some
 other type of administrative or access control framework.  However,
 there are operation status codes that allow an IPP server to return
 information back to a client about any potential access control
 violations for an IPP object.

deBry, et al. Experimental [Page 125] RFC 2566 IPP/1.0: Model and Semantics April 1999

 During a create operation, 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 8.3 below for more details.
 Since the security levels or the specific threats that any given IPP
 system administrator may be concerned with cannot be anticipated, IPP
 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, to none
 at all, and corresponding security mechanisms will be required. SSL3
 supports the type of negotiated levels of security required by most,
 if not all, potential IPP environments. IPP environments that require
 no security can elect to deploy IPP objects that do not utilize the
 optional SSL3 security mechanisms.

8.1 Security Scenarios

 The following sections describe specific security attacks for IPP
 environments.  Where examples are provided they should be considered
 illustrative of the environment and not an exhaustive set. Not all of
 these environments will necessarily be addressed in initial
 implementations of IPP.

8.1.1 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 work-group printers, or where batch applications print
 their output on large production printers. Although the identity of
 the user may be trusted in this environment, a user might want to
 protect the content of a document against such attacks as
 eavesdropping, replaying or tampering.

8.1.2 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,

deBry, et al. Experimental [Page 126] RFC 2566 IPP/1.0: Model and Semantics April 1999

 protection against eavesdropping and document tampering are also
 required. It will also be important in this environment to protect
 Printers against "spamming" and malicious document content.

8.1.3 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.
 Standard methods currently do not exist for remote entities to
 "assume" the credentials of a client for forwarding requests to a 3rd
 party. It is anticipated that Print-By-Reference will be used to
 access "public" documents and that sophisticated methods for
 authenticating "proxies" will not be specified for version 1 of IPP.

8.2 URIs for SSL3 and non-SSL3 Access

 As described earlier, an IPP object can support SSL3 access, non-SSL3
 access, or both.  The "printer-uri-supported" attribute contains the
 Printer object'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 object using one if its URIs.  This duality is not needed
 for Job objects, since the Printer objects is the factory for Job
 objects, and the Printer object will generate the correct URI for new
 Job objects depending on the Printer object's security configuration.

8.3 The "requesting-user-name" (name(MAX)) Operation Attribute

 Each operation MUST specify the user who is performing the operation
 in both of the following two ways:
   1) via the REQUIRED "requesting-user-name" operation attribute that
      a client SHOULD supply in all operations. The client MUST obtain
      the value for this attribute from an environmental or network
      login name for the user, rather than allowing the user to supply
      any value. If the client does not supply a value for
      "requesting-user-name", the printer MUST assume that the client
      is supplying some anonymous name, such as "anonymous".
   2) via an authentication mechanism of the underlying transport
      which may be configured to give no authentication information.

deBry, et al. Experimental [Page 127] RFC 2566 IPP/1.0: Model and Semantics April 1999

 There are six cases to consider:
   a) the authentication mechanism gives no information, and the
      client doesn't specify  "requesting-user-name".
   b) the authentication mechanism gives no information, but the
      client specifies "requesting-user-name".
   c) the authentication mechanism specifies a user which has no human
      readable representation, and the client doesn't specify
      "requesting-user-name".
   d) the authentication mechanism specifies a user which has no human
      readable representation, but the client specifies "requesting-
      user-name".
   e) the authentication mechanism specifies a user which has a human
      readable representation. The Printer object ignores the
      "requesting-user-name".
   f) the authentication mechanism specifies a user who is trusted and
      whose name means that the value of the "requesting-user-name",
      which MUST be present, is treated as the authenticated name.
 Note:  Case "f" is intended for a tightly coupled gateway and server
 to work together so that the "user" name is able to be that of the
 gateway client and not that of the gateway.  Because most, if not
 all, system vendors will initially implement IPP via a gateway into
 their existing print system, this mechanism is necessary unless the
 authentication mechanism allows a gateway (client) to act on behalf
 of some other client.
 The user-name has two forms:
  1. one that is human readable: it is held in the REQUIRED "job-

originating-user-name" Job Description attribute which is set

     during the job creation operations. It is used for presentation
     only, such as returning in queries or printing on start sheets
   - one for authorization: it is held in an undefined (by IPP) Job
     object attribute which is set by the job creation operation.  It
     is used to authorize other operations, such as Send-Document,
     Send-URI, Cancel-Job, to determine the user when the "my-jobs"
     attribute is specified with Get-Jobs, and to limit what
     attributes and values to return with Get-Job-Attributes and Get-
     Jobs.
 The human readable user name:
  1. is the value of the "requesting-user-name" for cases b, d and f.
  2. comes from the authentication mechanism for case e
  3. is some anonymous name, such as "anonymous" for cases a and c.
 The user name used for authorization:

deBry, et al. Experimental [Page 128] RFC 2566 IPP/1.0: Model and Semantics April 1999

  1. is the value of the "requesting-user-name" for cases b and f.
  2. comes from the authentication mechanism for cases c, d and e
  3. is some anonymous name, such as "anonymous" for case a.
 The essence of these rules for resolving conflicting sources of
 user-names is that a printer implementation is free to pick either
 source as long as it achieves consistent results.  That is, if a user
 uses the same path for a series of requests, the requests MUST appear
 to come from the same user from the standpoint of both the human-
 readable user name and the user name for authorization.  This rule
 MUST continue to apply even if a request could be authenticated by
 two or more mechanisms.  It doesn't matter which of  several
 authentication mechanisms a Printer uses as long as it achieves
 consistent results.  If a client uses more than one authentication
 mechanism, it is recommended that an administrator make all
 credentials resolve to the same user and user-name as much as
 possible.

8.4 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 may 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 on the object.

8.5 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, it is
 RECOMMENDED that such an implementation at least allow such "foreign"
 jobs to be queried using Get-Jobs returning "job-id" and "job-uri" as
 'unknown'.  Such an implementation NEED NOT 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.
 It is further RECOMMENDED, that the IPP Printer generate "job-id" and
 "job-uri" values for such "foreign jobs", if possible, so that they
 may 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

deBry, et al. Experimental [Page 129] RFC 2566 IPP/1.0: Model and Semantics April 1999

 foreign job to belong to 'anonymous'.  Only if the IPP client has
 been authenticated as an operator or administrator of the IPP Printer
 object, could the foreign jobs be queried by 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.

8.6 IPP Security Application Profile for SSL3

 The IPP application profile for SSL3 follows the "Secure Socket
 Layer" requirement as documented in the SSL3 specification [SSL].
 For interoperability, the SSL3 cipher suites are:
      SSL_RSA_WITH_RC4_128_MD5
      SSL_RSA_WITH_3DES_EDE_CBC_SHA
      SSL_RSA_WITH_DES_CBC_SHA
      SSL_RSA_EXPORT_WITH_RC4_40_MD5
      SSL_RSA_EXPORT_WITH_RC2_CBC_40_MD5
      SSL_RSA_WITH_NULL_MD5
 Client implementations MUST NOT assume any other cipher suites are
 supported by an IPP Printer object.
 If a conforming IPP object supports SSL3, it MUST implement and
 support the cipher suites listed above and MAY support additional
 cipher suites.
 A conforming IPP client SHOULD support SSL3 including the cipher
 suites listed above.  A conforming IPP client MAY support additional
 cipher suites.
 It is possible that due to certain government export restrictions
 some non-compliant versions of this extension could be deployed.
 Implementations wishing to inter-operate with such non-compliant
 versions MAY offer the SSL_RSA_EXPORT_WITH_RC4_40_MD5 and
 SSL_RSA_EXPORT_WITH_RC2_CBC_40_MD5 mechanisms.  However, since 40 bit
 ciphers are known to be vulnerable to attack by current technology,
 any client which actives a 40 bit cipher MUST NOT indicate to the
 user that the connection is completely secure from eavesdropping.

deBry, et al. Experimental [Page 130] RFC 2566 IPP/1.0: Model and Semantics April 1999

9. References

 [ASCII]      Coded Character Set - 7-bit American Standard Code for
              Information Interchange (ASCII), ANSI X3.4-1986. This
              standard is the specification of the US-ASCII charset.
 [HTPP]       J. Barnett, K. Carter, R. DeBry,  "Initial Draft -
              Hypertext Printing Protocol - HTPP/1.0", October 1996.
              ftp://ftp.pwg.org/pub/pwg/ipp/historic/htpp/
              overview.ps.gz
 [IANA-CS]    IANA Registry of Coded Character Sets:
              ftp://ftp.isi.edu/in-notes/iana/assignments/character-
              sets
 [IANA-MT]    IANA Registry of Media Types:  ftp://ftp.isi.edu/in-
              notes/iana/assignments/media-types/
 [ipp-iig]    Hastings, T. and C. Manros, "Internet Printing
              Protocol/1.0:  Implementer's Guide", Work in Progress.
 [ISO10646-1] ISO/IEC 10646-1:1993, "Information technology --
              Universal Multiple-Octet Coded Character Set (UCS) -
              Part 1: Architecture and Basic Multilingual Plane,
              JTC1/SC2."
 [ISO8859-1]  ISO/IEC 8859-1:1987, "Information technology -- 8-bit
              One-Byte Coded Character Set - Part 1: Latin Alphabet Nr
              1", 1987, JTC1/SC2.
 [ISO10175]   ISO/IEC 10175 Document Printing Application (DPA), June
              1996.
 [LDPA] T. Hastings, S. Isaacson, M. MacKay, C. Manros, D. Taylor, P.
              Zehler, "LDPA - Lightweight Document Printing
              Application", October 1996,
              ftp://ftp.pwg.org/pub/pwg/ipp/historic/ldpa/ldpa8.pdf.gz
 [P1387.4]    Kirk, M. (Editor), POSIX System Administration - Part 4:
              Printing Interfaces, POSIX 1387.4 D8, 1994.
 [PSIS]       Herriot, R. (editor), X/Open A Printing System
              Interoperability Specification (PSIS), August 1995.
 [PWG]        Printer Working Group, http://www.pwg.org.
 [RFC1035]    Mockapetris, P., "DOMAIN NAMES - IMPLEMENTATION AND
              SPECIFICATION", STD 13, RFC 1035, November 1987.

deBry, et al. Experimental [Page 131] RFC 2566 IPP/1.0: Model and Semantics April 1999

 [RFC1759]    Smith, R., Wright, F., Hastings, T., Zilles, S. and J.
              Gyllenskog, "Printer MIB", RFC 1759, March 1995.
 [RFC1766]    Alvestrand, H., "Tags for the Identification of
              Languages", RFC 1766, March 1995.
 [RFC1179]    McLaughlin, L. (Editor), "Line Printer Daemon Protocol",
              RFC 1179, August 1990.
 [RFC1952]    Deutsch, P., "GZIP file format specification version
              4.3", RFC 1952, May 1996.
 [RFC2045]    Freed, N. and N. Borenstein, " Multipurpose Internet
              Mail Extensions (MIME) Part One: Format of Internet
              Message Bodies", RFC 2045, November 1996.
 [RFC2046]    Freed, N. and N. Borenstein, "Multipurpose Internet Mail
              Extensions (MIME) Part Two: Media Types", RFC 2046,
              November 1996.
 [RFC2048]    Freed, N., Klensin, J. and J. Postel, "Multipurpose
              Internet Mail Extension (MIME) Part Four: Registration
              Procedures", RFC 2048, November 1996.
 [RFC2068]    Fielding, R., Gettys, J., Mogul, J., Frystyk, H. AND T.
              Berners-Lee, "Hypertext Transfer Protocol - HTTP/1.1",
              RFC 2068, January 1997.
 [RFC2069]    Franks, J., Hallam-Baker, P., Hostetler, J., Leach, P.,
              Luotonen, A., Sink, E. and L. Stewart, "An Extension to
              HTTP: Digest Access Authentication", RFC 2069, January
              1997.
 [RFC2119]    Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.
 [RFC2228]    Horowitz, M. and S. Lunt, "FTP Security Extensions", RFC
              2228, October 1997.
 [RFC2277]    Alvestrand, H., "IETF Policy on Character Sets and
              Languages" RFC 2277, January 1998.
 [RFC2278]    Freed, N. and J. Postel:  "IANA Charset Registration
              Procedures", BCP 19, RFC 2278, January 1998.
 [RFC2279]    Yergeau, F., "UTF-8, a transformation format of ISO
              10646", RFC 2279, January 1998.

deBry, et al. Experimental [Page 132] RFC 2566 IPP/1.0: Model and Semantics April 1999

 [RFC2316]    Bellovin, S., "Report of the IAB Security Architecture
              Workshop", RFC 2316, April 1998.
 [RFC2396]    Berners-Lee, T., Fielding, R. and L. Masinter, "Uniform
              Resource Identifiers (URI): Generic Syntax", RFC 2396,
              August 1998.
 [RFC2434]    Narten, T. and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs", BCP 26, RFC 2434,
              October 1998.
 [RFC2565]    Herriot, R., Butler, S., Moore, P. and R. Tuner
              "Internet Printing Protocol/1.0: Encoding and
              Transport", RFC 2565, April 1999.
 [RFC2567]    Wright, D.,  "Design Goals for an Internet Printing
              Protocol", RFC 2567, April 1999.
 [RFC2568]    Zilles, S., "Rationale for the Structure and Model and
              Protocol for the Internet Printing Protocol", RFC 2568,
              April 1999.
 [RFC2569]    Herriot, R., Hastings, T., Jacobs, N. and J. Martin,
              "Mapping between LPD and IPP Protocols", RFC 2569, April
              1999.
 [RFC2579]    McCloghrie, K., Perkins, D. and J. Schoenwaelder,
              "Textual Conventions for SMIv2", STD 58, RFC 2579, April
              1999.
 [SSL]        Netscape, The SSL Protocol, Version 3, (Text version
              3.02), November 1996.
 [SWP]        P. Moore, B. Jahromi, S. Butler, "Simple Web Printing
              SWP/1.0", May 7, 1997,
              ftp://ftp.pwg.org/pub/pwg/ipp/new_PRO/swp9705.pdf

deBry, et al. Experimental [Page 133] RFC 2566 IPP/1.0: Model and Semantics April 1999

10. Authors' Addresses

 Scott A. Isaacson (Editor)
 Novell, Inc.
 122 E 1700 S
 Provo, UT   84606
 Phone: 801-861-7366
 Fax:   801-861-2517
 EMail: sisaacson@novell.com
 Tom Hastings
 Xerox Corporation
 737 Hawaii St.
 El Segundo, CA   90245
 Phone: 310-333-6413
 Fax:   310-333-5514
 EMail: hastings@cp10.es.xerox.com
 Robert Herriot
 Xerox Corporation
 3400 Hillview Ave., Bldg #1
 Palo Alto, CA 94304
 Phone: 650-813-7696
 Fax:  650-813-6860
 EMail: robert.herriot@pahv.xerox.com
 Roger deBry
 Utah Valley State College
 Orem, UT 84058
 Phone: (801) 222-8000
 EMail: debryro@uvsc.edu

deBry, et al. Experimental [Page 134] RFC 2566 IPP/1.0: Model and Semantics April 1999

 Patrick Powell
 Astart Technologies
 9475 Chesapeake Dr., Suite D
 San Diego, CA  95123
 Phone: (619) 874-6543
 Fax: (619) 279-8424
 EMail: papowell@astart.com
 IPP Mailing List:  ipp@pwg.org
 IPP Mailing List Subscription: ipp-request@pwg.org
 IPP Web Page:  http://www.pwg.org/ipp/
 Implementers of this specification are encouraged to join IPP Mailing
 List in order to participate in any discussions of clarification
 issues and review of registration proposals for additional attributes
 and values.
 Other Participants:
    Chuck Adams - Tektronix
    Jeff Barnett - IBM
    Ron Bergman - Dataproducts Corp.
    Sylvan Butler - HP
    Keith Carter - IBM Corporation
    Jeff Copeland - QMS
    Andy Davidson - Tektronix
    Mabry Dozier - QMS
    Lee Farrell - Canon Information Systems
    Steve Gebert - IBM
    Babek Jahromi - Microsoft
    David Kellerman - Northlake Software
    Rick Landau - Digital
    Greg LeClair - Epson
    Harry Lewis - IBM
    Pete Loya - HP
    Ray Lutz - Cognisys
    Mike MacKay - Novell, Inc.
    Daniel Manchala - Xerox
    Carl-Uno Manros - Xerox
    Jay Martin - Underscore
    Larry Masinter - Xerox
    Stan McConnell - Xerox
    Ira McDonald - High North Inc.
    Paul Moore - Microsoft
    Tetsuya Morita - Ricoh
    Yuichi Niwa - Ricoh
    Pat Nogay - IBM

deBry, et al. Experimental [Page 135] RFC 2566 IPP/1.0: Model and Semantics April 1999

    Ron Norton - Printronics
    Bob Pentecost - HP
    Rob Rhoads - Intel
    Xavier Riley - Xerox
    David Roach - Unisys
    Stuart Rowley - Kyocera
    Hiroyuki Sato - Canon
    Bob Setterbo - Adobe
    Devon Taylor - Novell, Inc.
    Mike Timperman - Lexmark
    Randy Turner - Sharp
    Atsushi Yuki - Kyocera
    Rick Yardumian - Xerox
    Lloyd Young - Lexmark
    Bill Wagner - DPI
    Jim Walker - DAZEL
    Chris Wellens - Interworking Labs
    Rob Whittle - Novell, Inc.
    Don Wright - Lexmark
    Peter Zehler - Xerox
    Steve Zilles - Adobe

11. 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 6 for:
   1. type2 'keyword' attribute values
   2. type3 'keyword' attribute values
   3. type2 'enum' attribute values
   4. type3 'enum' attribute values
   5. attributes
   6. attribute syntaxes
   7. operations
   8. status codes

11.1 Type2 keyword attribute values 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 IPP Model
 Section 4.1.2.3):
 Name of proposer:

deBry, et al. Experimental [Page 136] RFC 2566 IPP/1.0: Model and Semantics April 1999

 Address of proposer:
 Email address of proposer:
 Note:  For type2 keywords, the Designated Expert will be the point of
 contact for the approved registration specification, if any
 maintenance of the registration specification is needed.

11.2 Type3 keyword attribute values registration

 Type of registration:  type3 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 IPP Model
 Section 4.1.2.3):
 Name of proposer:
 Address of proposer:
 Email address of proposer:
 Note:  For type3 keywords, the proposer will be the point of contact
 for the approved registration specification, if any maintenance of
 the registration specification is needed.

11.3 Type2 enum attribute values 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 IPP Model
 Section 4.1.4):
 Name of proposer:
 Address of proposer:
 Email address of proposer:
 Note:  For type2 enums, the Designated Expert will be the point of
 contact for the approved registration specification, if any
 maintenance of the registration specification is needed.

11.4 Type3 enum attribute values registration

 Type of registration:  type3 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 IPP Model
 Section 4.1.4):

deBry, et al. Experimental [Page 137] RFC 2566 IPP/1.0: Model and Semantics April 1999

 Name of proposer:
 Address of proposer:
 Email address of proposer:
 Note:  For type3 enums, the proposer will be the point of contact for
 the approved registration specification, if any maintenance of the
 registration specification is needed.

11.5 Attribute registration

 Type of registration:  attribute
 Proposed keyword name of this attribute:
 Types of attribute (Operation, Job Template, Job Description,
 Printer Description):
 Operations to be used with if the attribute is an operation
 attribute:
 Object (Job, Printer, etc. if bound to an object):
 Attribute syntax(es) (include 1setOf and range as in Section 4.2):
 If attribute syntax is 'keyword' or 'enum', is it type2 or type3:
 If this is a Printer attribute, MAY the value returned depend on
 "document-format" (See Section 6.2):
 If this is a Job Template attribute, how does its specification
 depend on the value of the "multiple-document-handling" attribute:
 Specification of this attribute (follow the style of IPP Model
 Section 4.2):
 Name of proposer:
 Address of proposer:
 Email address of proposer:
 Note:  For attributes, the IPP Designated Expert will be the point of
 contact for the approved registration specification, if any
 maintenance of the registration specification is needed.

11.6 Attribute Syntax registration

 Type of registration:  attribute syntax
 Proposed name of this attribute syntax:
 Type of attribute syntax (integer, octetString, character-string,
 see [RFC2565]):
 Numeric value (to be assigned by the IPP Designated Expert in
 consultation with IANA):
 Specification of this attribute (follow the style of IPP Model
 Section 4.1):
 Name of proposer:
 Address of proposer:
 Email address of proposer:

deBry, et al. Experimental [Page 138] RFC 2566 IPP/1.0: Model and Semantics April 1999

 Note:  For attribute syntaxes, the IPP Designated Expert will be the
 point of contact for the approved registration specification, if any
 maintenance of the registration specification is needed.

11.7 Operation registration

 Type of registration:  operation
 Proposed name of this operation:
 Numeric operation-id value (to be assigned by the IPP Designated
 Expert in consultation with IANA):
 Object Target (Job, Printer, etc. that operation is upon):
 Specification of this attribute (follow the style of IPP Model
 Section 3):
 Name of proposer:
 Address of proposer:
 Email address of proposer:
 Note:  For operations, the IPP Designated Expert will be the point of
 contact for the approved registration specification, if any
 maintenance of the registration specification is needed.

11.8 Attribute Group registration

 Type of registration:  attribute group
 Proposed name of this attribute group:
 Numeric tag according to [RFC2565] (to be assigned by the IPP
 Designated Expert in consultation with IANA):
 Operation requests and group number for each operation in which the
 attribute group occurs:
 Operation responses and group number for each operation in which the
 attribute group occurs:
 Specification of this attribute group (follow the style of IPP Model
 Section 3):
 Name of proposer:
 Address of proposer:
 Email address of proposer:
 Note:  For attribute groups, the IPP Designated Expert will be the
 point of contact for the approved registration specification, if any
 maintenance of the registration specification is needed.

11.9 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 may be used with:

deBry, et al. Experimental [Page 139] RFC 2566 IPP/1.0: Model and Semantics April 1999

 Specification of this status code (follow the style of IPP Model
 Section 14 APPENDIX B:  Status Codes and Suggested Status Code
 Messages):
 Name of proposer:
 Address of proposer:
 Email address of proposer:
 Note:  For status codes, the Designated Expert will be the point of
 contact for the approved registration specification, if any
 maintenance of the registration specification is needed.

deBry, et al. Experimental [Page 140] RFC 2566 IPP/1.0: Model and Semantics April 1999

12. APPENDIX A: Terminology

 This specification uses the terminology defined in this section.

12.1 Conformance Terminology

 The key words "MUST", "MUST NOT", "REQUIRED", "SHOULD", "SHOULD NOT",
 "RECOMMENDED", "MAY", and  "OPTIONAL" in this document are to be
 interpreted as described in RFC 2119 [RFC2119].

12.1.1 NEED NOT

 This term is not included in RFC 2119.  The verb "NEED NOT" indicates
 an action that the subject of the sentence does not have to implement
 in order to claim conformance to the standard.  The verb "NEED NOT"
 is used instead of "MAY NOT" since "MAY NOT" sounds like a
 prohibition.

12.2 Model Terminology

12.2.1 Keyword

 Keywords are used within this document as identifiers of semantic
 entities within the abstract model (see section 4.1.2.3).  Attribute
 names, some attribute values, attribute syntaxes, and attribute group
 names are represented as keywords.

12.2.2 Attributes

 An attribute is an item of information that is associated with an
 instance of an IPP object.  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 4 and
 all operation attributes are defined in section 3.
 Job Template Attributes are described in section 4.2. The client
 optionally supplies Job Template attributes in a create request
 (operation requests that create Job objects).  The Printer object has
 associated attributes which define supported and default values for
 the Printer.

12.2.2.1 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 header describing that

deBry, et al. Experimental [Page 141] RFC 2566 IPP/1.0: Model and Semantics April 1999

 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.

12.2.2.2 Attribute Group Name

 Related attributes are grouped into named groups.  The name of the
 group is a keyword.  The group name may be used in place of naming
 all the attributes in the group explicitly.  Attribute groups are
 defined in section 3.

12.2.2.3 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.

12.2.2.4 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 [RFC2565] indicates the
 actual "on-the-wire" encoding rules for each syntax type.  Attribute
 syntax types are defined in section 4.1.

12.2.3 Supports

 By definition, a Printer object supports an attribute only if that
 Printer object responds with the corresponding attribute populated
 with some value(s) in a response to a query for that attribute.  A
 Printer object supports an attribute value if the value is one of the
 Printer object's "supported values" attributes.  The device behind a
 Printer object may exhibit a behavior that corresponds to some IPP
 attribute, but if the Printer object, 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 object'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 object does not support that particular
 value.
 A conforming implementation MUST support 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

deBry, et al. Experimental [Page 142] RFC 2566 IPP/1.0: Model and Semantics April 1999

 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, possibly
 only one, taken from the entire set of possible values defined for
 that attribute. This limited set of values 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 which 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 "finishings-supported" attribute.
   1) If a Printer object is not physically capable of stapling, the
      "finishings-supported" attribute MUST NOT be populated with the
      value of 'staple'.
   2) A Printer object 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 object 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 object 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 object attribute. Doing
      so, would enable 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 object
 is OPTIONAL, it is RECOMMENDED that if the device behind a Printer
 object is capable of realizing any feature or function that
 corresponds to an IPP attribute and some associated value, then that
 implementation SHOULD support that IPP attribute and value.

deBry, et al. Experimental [Page 143] RFC 2566 IPP/1.0: Model and Semantics April 1999

 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 IPP.  For administrative
 policy and control reasons, an administrator may 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 may be
 capable of a certain feature, however an administrator is specifying
 that access to that feature not be exposed to the end user through
 the IPP protocol.  Also, since a Printer object may 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 object supports a value, some
 manual human action may 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 object.
 For another example of how supported attributes function, consider a
 system 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 system 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 create 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 create request is rejected or the "job-
 sheets" value is ignored (again depending on the value of "ipp-
 attribute-fidelity").

12.2.4 print-stream page

 A "print-stream page" is a page according to the definition of pages
 in the language used to express the document data.

12.2.5 impression

 An "impression" is the image (possibly many print-stream pages in
 different configurations) imposed onto a single media page.

deBry, et al. Experimental [Page 144] RFC 2566 IPP/1.0: Model and Semantics April 1999

13. APPENDIX B: Status Codes 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.  Since the status message is an OPTIONAL component of the
 operation response, an IPP application (i.e., a browser, GUI, print
 driver or gateway) is NOT REQUIRED to examine or display the status
 message, since it MAY not be returned to the application.
 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 must be 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 codes are extensible.  IPP clients
 are NOT REQUIRED to understand the meaning of all registered status
 codes, though such understanding is obviously desirable.  However,
 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.  In such cases, IPP applications
 SHOULD present the OPTIONAL message (if present) to the end user
 since the message is likely to contain human readable information
 which will help to explain the unusual status.  The name of the enum
 is the suggested status message for US English.
 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" - 0x0200 to 0x02FF

deBry, et al. Experimental [Page 145] RFC 2566 IPP/1.0: Model and Semantics April 1999

   "client-error" - 0x0400 to 0x04FF
   "server-error" - 0x0500 to 0x05FF
 The top half (128 values) of each range (0x0n40 to 0x0nFF, for n = 0
 to 5) is reserved for private use within each status code class.
 Values 0x0600 to 0x7FFF are reserved for future assignment and MUST
 NOT be used.

13.1 Status Codes

 Each status code is described below. Section 13.1.5.9 contains a
 table that indicates which status codes apply to which operations.
 The Implementer's Guide [ipp-iig] describe the suggested steps for
 processing IPP attributes for all operations, including returning
 status codes.

13.1.1 Informational

 This class of status code indicates a provisional response and is to
 be used for informational purposes only.
 There are no status codes defined in IPP/1.0 for this class of status
 code.

13.1.2 Successful Status Codes

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

13.1.2.1 successful-ok (0x0000)

 The request has succeeded and no request attributes were substituted
 or ignored.  In the case of a response to a create 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.

13.1.2.2 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

deBry, et al. Experimental [Page 146] RFC 2566 IPP/1.0: Model and Semantics April 1999

 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 MAY, but
 is NOT REQUIRED to, return the "requested-attributes" attribute in
 the Unsupported Attribute response group (with the unsupported values
 only).  See section 3.2.1.2.

13.1.2.3 successful-ok-conflicting-attributes (0x0002)

 The request has succeeded, but some supplied attribute values
 conflicted with the values of other supplied attributes.  These
 conflicting values were either (1) substituted with (supported)
 values or (2) the attributes were removed in order to process the job
 without rejecting it.  Attributes or values which 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 section 3.2.1.2.

13.1.3 Redirection Status Codes

 This class of status code indicates that further action needs to be
 taken to fulfill the request.
 There are no status codes defined in IPP/1.0 for this class of status
 code.

13.1.4 Client Error Status Codes

 This class of status code 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.

13.1.4.1 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 Implementer's Guide [ipp-iig] ).  The IPP application SHOULD NOT
 repeat the request without modifications.

13.1.4.2 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

deBry, et al. Experimental [Page 147] RFC 2566 IPP/1.0: Model and Semantics April 1999

 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.

13.1.4.3 client-error-not-authenticated (0x0402)

 The request requires user authentication.  The IPP client may 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 may contain relevant diagnostic
 information.  This status codes reveals more information than
 "client-error-forbidden".

13.1.4.4 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 codes reveals
 more information than "client-error-forbidden" and "client-error-
 not-authenticated".

13.1.4.5 client-error-not-possible (0x0404)

 This status code is used when the request is for something that can
 not 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.

13.1.4.6 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 and this error status code was returned in
 response to the Send-Document request  (see section 3.3.1).  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.

deBry, et al. Experimental [Page 148] RFC 2566 IPP/1.0: Model and Semantics April 1999

13.1.4.7 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 mean time 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 can not 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 can not 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.

13.1.4.8 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.

13.1.4.9 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.

deBry, et al. Experimental [Page 149] RFC 2566 IPP/1.0: Model and Semantics April 1999

13.1.4.10 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 has 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 may pass the value onto some other system component
 which is not able to accept the large value.  For more details, see
 the Implementer's Guide [ipp-iig] .
 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.

13.1.4.11 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 object.
 This error is returned independent of the client-supplied "ipp-
 attribute-fidelity".  The Printer object MUST return this status
 code, even if there are other attributes that are not supported as
 well, since this error is a bigger problem than with Job Template
 attributes.

13.1.4.12 client-error-attributes-or-values-not-supported (0x040B)

 In a create request, if the Printer object does not support one or
 more attributes, attribute syntaxes, or attribute values supplied in
 the request and the client supplied the "ipp-attributes-fidelity"
 operation attribute with the 'true' value, the Printer object MUST
 return this status code.  For example, if the request indicates '
 iso-a4' media, but that media type is not supported by the Printer
 object.  Or, if the client supplies an optional 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 attributes and values rather than
 reject the request and return this status code.

deBry, et al. Experimental [Page 150] RFC 2566 IPP/1.0: Model and Semantics April 1999

 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 MAY return the unsupported attributes as
 values of the "requested-attributes" in the Unsupported Attributes
 Group (see section 13.1.2.2).

13.1.4.13 client-error-uri-scheme-not-supported (0x040C)

 The type of the client supplied URI in a Print-URI or a Send-URI
 operation is not supported.

13.1.4.14 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 and any 'text' or 'name' attributes using the 'utf-8' charset
 (see Section 3.1.4.1).

13.1.4.15 client-error-conflicting-attributes (0x040E)

 The request is rejected because some attribute values conflicted with
 the values of other attributes which this specification does not
 permit to be substituted or ignored.

13.1.5 Server Error Status Codes

 This class of status codes 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.

13.1.5.1 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 probably some knowledgeable human
 intervention is required.

deBry, et al. Experimental [Page 151] RFC 2566 IPP/1.0: Model and Semantics April 1999

13.1.5.2 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.

13.1.5.3 server-error-service-unavailable (0x0502)

 The IPP object is currently unable to handle the request due to a
 temporary overloading or maintenance of the IPP object.  The
 implication is that this is a temporary condition which will be
 alleviated after some delay. If known, the length of the delay may 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
 error status codes "client-error-gone" or "client-error-not-found"
 could be used.

13.1.5.4 server-error-version-not-supported (0x0503)

 The IPP object does not support, or refuses to support, the IPP
 protocol version that was used in the request message.  The IPP
 object is indicating that it is unable or unwilling to complete the
 request using the same version as supplied in the request other than
 with this error message. The response should contain a Message
 describing why that version is not supported and what other versions
 are supported by that IPP object.
 A conforming IPP/1.0 client MUST specify the valid version ('1.0') on
 each request.  A conforming IPP/1.0 object MUST NOT return this
 status code to a conforming IPP/1.0 client.  An IPP object MUST
 return this status code to a non-conforming IPP client.  The response
 MUST identify in the "version-number" operation attribute the closest
 version number that the IPP object does support.

13.1.5.5 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
 create 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 create request is that the printer
 currently has a paper jam.  In many cases however, where the Printer

deBry, et al. Experimental [Page 152] RFC 2566 IPP/1.0: Model and Semantics April 1999

 object 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.

13.1.5.6 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 may have been cleared.  Alternatively, as an
 implementation option, a Printer object MAY delay the response until
 the temporary condition is cleared so that no error is returned.

13.1.5.7 server-error-not-accepting-jobs (0x0506)

 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-not-accepting-jobs" attribute to 'false' (by
 means outside of IPP/1.0).

13.1.5.8 server-error-busy (0x0507)

 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.

13.1.5.9 server-error-job-canceled (0x0508)

 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 and job-uri 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 are returned in the response.

13.2 Status Codes 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

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                                                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
 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

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14. APPENDIX C: "media" keyword values

 Standard keyword values are taken from several sources.
 Standard values are defined (taken from DPA[ISO10175] and the Printer
 MIB[RFC1759]):
   'default': The default medium for the output device
   'iso-a4-white': Specifies the ISO A4 white medium
   'iso-a4-colored': Specifies the ISO A4 colored medium
   'iso-a4-transparent' Specifies the ISO A4 transparent medium
   'iso-a3-white': Specifies the ISO A3 white medium
   'iso-a3-colored': Specifies the ISO A3 colored medium
   'iso-a5-white': Specifies the ISO A5 white medium
   'iso-a5-colored': Specifies the ISO A5 colored medium
   'iso-b4-white': Specifies the ISO B4 white medium
   'iso-b4-colored': Specifies the ISO B4 colored medium
   'iso-b5-white': Specifies the ISO B5 white medium
   'iso-b5-colored': Specifies the ISO B5 colored medium
   'jis-b4-white': Specifies the JIS B4 white medium
   'jis-b4-colored': Specifies the JIS B4 colored medium
   'jis-b5-white': Specifies the JIS B5 white medium
   'jis-b5-colored': Specifies the JIS B5 colored medium
 The following standard values are defined for North American media:
   'na-letter-white': Specifies the North American letter white medium
   'na-letter-colored': Specifies the North American letter colored
      medium
   'na-letter-transparent': Specifies the North American letter
      transparent medium
   'na-legal-white': Specifies the North American legal white medium
   'na-legal-colored': Specifies the North American legal colored
      medium
 The following standard values are defined for envelopes:
   'iso-b4-envelope': Specifies the ISO B4 envelope medium
   'iso-b5-envelope': Specifies the ISO B5 envelope medium
   'iso-c3-envelope': Specifies the ISO C3 envelope medium
   'iso-c4-envelope': Specifies the ISO C4 envelope medium
   'iso-c5-envelope': Specifies the ISO C5 envelope medium
   'iso-c6-envelope': Specifies the ISO C6 envelope medium
   'iso-designated-long-envelope': Specifies the ISO Designated Long
      envelope medium
   'na-10x13-envelope': Specifies the North American 10x13 envelope
      medium

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   'na-9x12-envelope': Specifies the North American 9x12 envelope
      medium
   'monarch-envelope': Specifies the Monarch envelope
   'na-number-10-envelope': Specifies the North American number 10
      business envelope medium
   'na-7x9-envelope': Specifies the North American 7x9 inch envelope
   'na-9x11-envelope': Specifies the North American 9x11 inch envelope
   'na-10x14-envelope': Specifies the North American 10x14 inch
      envelope
   'na-number-9-envelope': Specifies the North American number 9
      business envelope
   'na-6x9-envelope': Specifies the North American 6x9 inch envelope
   'na-10x15-envelope': Specifies the North American 10x15 inch
      envelope
 The following standard values are defined for the less commonly used
 media (white-only):
   'executive-white': Specifies the white executive medium
   'folio-white': Specifies the folio white medium
   'invoice-white': Specifies the white invoice medium
   'ledger-white': Specifies the white ledger medium
   'quarto-white': Specified the white quarto medium
   'iso-a0-white': Specifies the ISO A0 white medium
   'iso-a1-white': Specifies the ISO A1 white medium
   'iso-a2-white': Specifies the ISO A2 white medium
   'iso-a6-white': Specifies the ISO A6 white medium
   'iso-a7-white': Specifies the ISO A7 white medium
   'iso-a8-white': Specifies the ISO A8 white medium
   'iso-a9-white': Specifies the ISO A9 white medium
   'iso-10-white': Specifies the ISO A10 white medium
   'iso-b0-white': Specifies the ISO B0 white medium
   'iso-b1-white': Specifies the ISO B1 white medium
   'iso-b2-white': Specifies the ISO B2 white medium
   'iso-b3-white': Specifies the ISO B3 white medium
   'iso-b6-white': Specifies the ISO B6 white medium
   'iso-b7-white': Specifies the ISO B7 white medium
   'iso-b8-white': Specifies the ISO B8 white medium
   'iso-b9-white': Specifies the ISO B9 white medium
   'iso-b10-white': Specifies the ISO B10 white medium
   'jis-b0-white': Specifies the JIS B0 white medium
   'jis-b1-white': Specifies the JIS B1 white medium
   'jis-b2-white': Specifies the JIS B2 white medium
   'jis-b3-white': Specifies the JIS B3 white medium
   'jis-b6-white': Specifies the JIS B6 white medium
   'jis-b7-white': Specifies the JIS B7 white medium

deBry, et al. Experimental [Page 156] RFC 2566 IPP/1.0: Model and Semantics April 1999

   'jis-b8-white': Specifies the JIS B8 white medium
   'jis-b9-white': Specifies the JIS B9 white medium
   'jis-b10-white': Specifies the JIS B10 white medium
 The following standard values are defined for engineering media:
   'a': Specifies the engineering A size medium
   'b': Specifies the engineering B size medium
   'c': Specifies the engineering C size medium
   'd': Specifies the engineering D size medium
   'e': Specifies the engineering E size medium
 The following standard values are defined for input-trays (from ISO
 DPA and the Printer MIB):
   'top': The top input tray in the printer.
   'middle': The middle input tray in the printer.
   'bottom': The bottom input tray in the printer.
   'envelope': The envelope input tray in the printer.
   'manual': The manual feed input tray in the printer.
   'large-capacity': The large capacity input tray in the printer.
   'main': The main input tray
   'side': The side input tray
 The following standard values are defined for media sizes (from ISO
 DPA):
   'iso-a0': Specifies the ISO A0 size: 841 mm by 1189 mm as defined
      in ISO 216
   'iso-a1': Specifies the ISO A1 size: 594 mm by 841 mm as defined in
      ISO 216
   'iso-a2': Specifies the ISO A2 size: 420 mm by 594 mm as defined in
      ISO 216
   'iso-a3': Specifies the ISO A3 size: 297 mm by 420 mm as defined in
      ISO 216
   'iso-a4': Specifies the ISO A4 size: 210 mm by 297 mm as defined in
      ISO 216
   'iso-a5': Specifies the ISO A5 size: 148 mm by 210 mm as defined in
      ISO 216
   'iso-a6': Specifies the ISO A6 size: 105 mm by 148 mm as defined in
      ISO 216
   'iso-a7': Specifies the ISO A7 size: 74 mm by 105 mm as defined in
      ISO 216
   'iso-a8': Specifies the ISO A8 size: 52 mm by 74 mm as defined in
      ISO 216

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   'iso-a9': Specifies the ISO A9 size: 37 mm by 52 mm as defined in
      ISO 216
   'iso-a10': Specifies the ISO A10 size: 26 mm by 37 mm as defined in
      ISO 216
   'iso-b0': Specifies the ISO B0 size: 1000 mm by 1414 mm as defined
      in ISO 216
   'iso-b1': Specifies the ISO B1 size: 707 mm by 1000 mm as defined
      in ISO 216
   'iso-b2': Specifies the ISO B2 size: 500 mm by 707 mm as defined in
      ISO 216
   'iso-b3': Specifies the ISO B3 size: 353 mm by 500 mm as defined in
      ISO 216
   'iso-b4': Specifies the ISO B4 size: 250 mm by 353 mm as defined in
      ISO 216
   'iso-b5': Specifies the ISO B5 size: 176 mm by 250 mm as defined in
      ISO 216
   'iso-b6': Specifies the ISO B6 size: 125 mm by 176 mm as defined in
      ISO 216
   'iso-b7': Specifies the ISO B7 size: 88 mm by 125 mm as defined in
      ISO 216
   'iso-b8': Specifies the ISO B8 size: 62 mm by 88 mm as defined in
      ISO 216
   'iso-b9': Specifies the ISO B9 size: 44 mm by 62 mm as defined in
      ISO 216
   'iso-b10': Specifies the ISO B10 size: 31 mm by 44 mm as defined in
      ISO 216
   'na-letter': Specifies the North American letter size: 8.5 inches by
      11 inches
   'na-legal': Specifies the North American legal size: 8.5 inches by
      14 inches
   'executive': Specifies the executive size (7.25 X 10.5 in)
   'folio': Specifies the folio size (8.5 X 13 in)
   'invoice': Specifies the invoice size (5.5 X 8.5 in)
   'ledger': Specifies the ledger size (11 X 17 in)
   'quarto': Specifies the quarto size (8.5 X 10.83 in)
   'iso-c3': Specifies the ISO C3 size: 324 mm by 458 mm as defined in
      ISO 269
   'iso-c4': Specifies the ISO C4 size: 229 mm by 324 mm as defined in
      ISO 269
   'iso-c5': Specifies the ISO C5 size: 162 mm by 229 mm as defined in
      ISO 269
   'iso-c6': Specifies the ISO C6 size: 114 mm by 162 mm as defined in
      ISO 269
   'iso-designated-long': Specifies the ISO Designated Long size: 110
      mm by 220 mm as defined in ISO 269
   'na-10x13-envelope': Specifies the North American 10x13 size: 10
      inches by 13 inches

deBry, et al. Experimental [Page 158] RFC 2566 IPP/1.0: Model and Semantics April 1999

   'na-9x12-envelope': Specifies the North American 9x12 size: 9
      inches by 12 inches
   'na-number-10-envelope': Specifies the North American number 10
      business envelope size: 4.125 inches by 9.5 inches
   'na-7x9-envelope': Specifies the North American 7x9 inch envelope
      size
   'na-9x11-envelope': Specifies the North American 9x11 inch envelope
      size
   'na-10x14-envelope': Specifies the North American 10x14 inch
      envelope size
   'na-number-9-envelope': Specifies the North American number 9
      business envelope size
   'na-6x9-envelope': Specifies the North American 6x9 envelope size
   'na-10x15-envelope': Specifies the North American 10x15 envelope
      size
   'monarch-envelope': Specifies the Monarch envelope size (3.87 x 7.5
      in)
   'jis-b0': Specifies the JIS B0 size: 1030mm x 1456mm
   'jis-b1': Specifies the JIS B1 size: 728mm x 1030mm
   'jis-b2': Specifies the JIS B2 size: 515mm x 728mm
   'jis-b3': Specifies the JIS B3 size: 364mm x 515mm
   'jis-b4': Specifies the JIS B4 size: 257mm x 364mm
   'jis-b5': Specifies the JIS B5 size: 182mm x 257mm
   'jis-b6': Specifies the JIS B6 size: 128mm x 182mm
   'jis-b7': Specifies the JIS B7 size: 91mm x 128mm
   'jis-b8': Specifies the JIS B8 size: 64mm x 91mm
   'jis-b9': Specifies the JIS B9 size: 45mm x 64mm
   'jis-b10': Specifies the JIS B10 size: 32mm x 45mm

deBry, et al. Experimental [Page 159] RFC 2566 IPP/1.0: Model and Semantics April 1999

15. APPENDIX D: Processing IPP Attributes

 When submitting a print job to a Printer object, the IPP model allows
 a client to supply operation and Job Template attributes along with
 the document data.  These Job Template attributes in the create
 request affect the rendering, production and finishing of the
 documents in the job.  Similar types of instructions may also be
 contained in the document to be printed, that is, embedded within the
 print data itself.  In addition, the Printer has a set of attributes
 that describe what rendering and finishing options which are
 supported by that Printer.  This model, which allows for flexibility
 and power, also introduces the potential that at job submission time,
 these client-supplied attributes may conflict with either:
  1. what the implementation is capable of realizing (i.e., what the

Printer supports), as well as

  1. the instructions embedded within the print data itself.
 The following sections describe how these two types of conflicts are
 handled in the IPP model.

15.1 Fidelity

 If there is a conflict between what the client requests and what a
 Printer object supports, the client may request one of two possible
 conflict handling mechanisms:
   1) either reject the job since the job can not 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 to the Printer object:
 "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 to the Printer object: "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 client supplied attributes need to be changed or ignored."
 The IPP model accounts for this situation by introducing an "ipp-
 attribute-fidelity" attribute.
 In a create request, "ipp-attribute-fidelity" is a boolean operation
 attribute that is OPTIONALLY 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

deBry, et al. Experimental [Page 160] RFC 2566 IPP/1.0: Model and Semantics April 1999

 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
 them or substitute any supported value for unsupported values,
 respectively.  The Printer may 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', the Printer may
 choose to substitute 'iso-a4' rather than a default value of '
 envelope'. 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'):
  1. If the client supplies 'false' or does not supply the attribute,

the Printer object MUST always accept the request by ignoring

     unsupported Job Template attributes and by substituting
     unsupported values of supported Job Template attributes with
     supported values.
   - If the client supplies 'true', the Printer object 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 sub-optimal result to nothing
      at all.
   3) The End User just wants something reasonable in lieu of nothing
      at all.

15.2 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 were a previously formatted document has embedded in it

deBry, et al. Experimental [Page 161] RFC 2566 IPP/1.0: Model and Semantics April 1999

 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'.  The job submission attribute should take precedence over
 the embedded PDL instruction.  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 objects
 capabilities to override instructions embedded in the PDL data
 stream.  The value of the "pdl-override-supported" attribute is
 configured by means outside IPP/1.0.
 This REQUIRED Printer attribute takes on the following values:
  1. 'attempted': This value indicates that the Printer object

attempts to make the IPP attribute values take precedence over

     embedded instructions in the document data, however there is no
     guarantee.
   - 'not-attempted': This value indicates that the Printer object
     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.
   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 object 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.

deBry, et al. Experimental [Page 162] RFC 2566 IPP/1.0: Model and Semantics April 1999

 At job processing time, an implementation that supports the value of
 'not-attempted' might do one of the following actions:
   1) Simply pre-pend 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 object pre-pended.  In other words,
      this implementation is using the same implementation semantics
      for the client-supplied IPP attributes as for the Printer object
      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
 can not 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 may fail to affect the Job
 processing and output when the corresponding instruction is embedded
 in the document data.

15.3 Using Job Template Attributes During Document Processing.

 The Printer object uses some of the Job object's Job Template
 attributes during the processing of the document data associated with
 that job.  These include, but are not limited to, "orientation",
 "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 and any alternative steps that accomplishes
 the same effect can be used to implement this specification.
   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 or

deBry, et al. Experimental [Page 163] RFC 2566 IPP/1.0: Model and Semantics April 1999

      not 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 specification. The formatting of the document
      data uses the "orientation-requested" attribute to determine how
      the formatted print data should be placed on a print-stream
      page, see section 4.2.10 for the details.
   2. The document data is in the form of a print-stream in a known
      media type. The "page-ranges" attribute is used to select, as
      specified in section 4.2.7, a sub-sequence of the pages in the
      print-stream that are to be processed and images.
   3. The input to this step is a sequence of print-stream pages. This
      step is controlled by the "number-up" attribute. If the value of
      "number-up" is N, then during the processing of the print-stream
      pages, each N print-stream pages are positioned, as specified in
      section 4.2.9, to create a single impression. If a given
      document does not have N more print-stream pages, then the
      completion of the impression is controlled by the "multiple-
      document-handling" attribute as described in section 4.2.4; when
      the value of this attribute is 'single-document' or 'single-
      document-new-sheet', the print-stream pages of document data
      from subsequent documents is used to complete the impression.
      The size(scaling), position(translation) and rotation of the
      print-stream pages on the impression is implementation defined.
      Note that during this process the print-stream pages may 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 4.2.12 and 4.2.13. In the case N=1, the impression is
      nearly the same as the print-stream page; the differences would
      only be in the size, position and rotation of the print-stream
      page and/or any decoration, such as a frame to the page, that is
      added by the implementation.
   4. 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 print-stream page, as
      described in section 4.2.8. The orientation of the print-stream
      pages affects the orientation of the impression; for example, if
      "number-up" equals 2, then, typically, two portrait print-stream
      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
      4.2.4.

deBry, et al. Experimental [Page 164] RFC 2566 IPP/1.0: Model and Semantics April 1999

   5. The "copies" and "multiple-document-handling" attributes are
      used to determine how many copies of each media instance are
      created and in what order. See sections 4.2.5 and 4.2.4 for the
      details.
   6. When the correct number of copies are created, the media
      instances are finished according to the values of the
      "finishings" attribute as described in 4.2.6. Note that
      sometimes finishing operations may require manual intervention
      to perform the finishing operations on the copies, especially
      uncollated copies. This specification allows any or all of the
      processing steps to be performed automatically or manually at
      the discretion of the Printer object.

deBry, et al. Experimental [Page 165] RFC 2566 IPP/1.0: Model and Semantics April 1999

16. APPENDIX E: Generic Directory Schema

 This section defines a generic schema for an entry in a directory
 service.  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.  IPP 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.
 Note: Some directory implementations allow for the notion of
 "aliasing".  That is, one directory entry object can appear as
 multiple directory entry object 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 object.
 The generic schema is a subset of IPP Printer Job Template and
 Printer Description attributes (sections 4.2 and 4.4).  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 Printers
 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
 object.
 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
 object, one of the RECOMMENDED directory entry attributes is the
 Printer object's "printer-uri-supported" attribute.  The IPP client
 queries the "printer-uri-supported" attribute in the directory entry

deBry, et al. Experimental [Page 166] RFC 2566 IPP/1.0: Model and Semantics April 1999

 and then addresses the IPP Printer object using one of its URIs.  The
 "uri-security-supported" attribute identifies the protocol (if any)
 used to secure a channel.
 The following attributes define the generic schema for directory
 entries of type PRINTER:
   printer-uri-supported           RECOMMENDED    Section 4.4.1
   uri-security-supported          RECOMMENDED    Section 4.4.2
   printer-name                    RECOMMENDED    Section 4.4.3
   printer-location                RECOMMENDED    Section 4.4.4
   printer-info                    OPTIONAL       Section 4.4.5
   printer-more-info               OPTIONAL       Section 4.4.6
   printer-make-and-model          RECOMMENDED    Section 4.4.8
   charset-supported               OPTIONAL       Section 4.4.15
   generated-natural-language-
      supported                    OPTIONAL       Section 4.4.17
   document-format-supported       RECOMMENDED    Section 4.4.19
   color-supported                 RECOMMENDED    Section 4.4.23
   finishings-supported            OPTIONAL       Section 4.2.6
   number-up-supported             OPTIONAL       Section 4.2.7
   sides-supported                 RECOMMENDED    Section 4.2.8
   media-supported                 RECOMMENDED    Section 4.2.11
   printer-resolution-supported    OPTIONAL       Section 4.2.12
   print-quality-supported         OPTIONAL       Section 4.2.13

deBry, et al. Experimental [Page 167] RFC 2566 IPP/1.0: Model and Semantics April 1999

17. APPENDIX F: Change History for the IPP Model and Semantics document

 The following substantive changes and major clarifications have been
 made to this document from the June 30, 1998 version based on the
 interoperability testing that took place September 23-25 1998 and
 subsequent mailing list and meeting discussions.  They are listed in
 the order of occurrence in the document.  These changes are the ones
 that might affect implementations.  Clarifications that are unlikely
 to affect implementations are not listed.  The issue numbers refer to
 the IPP Issues List which is available in the following directory:
      ftp://ftp.pwg.org/pub/pwg/ipp/approved-clarifications/
 Section   Description
 global    Replaced TLS references with SSL3 references as agreed with
           our Area Director on 11/12/1998.
 global    Removed the indications that some of these IPP documents
           are informational, since the intent is now to publish all
           IPP/1.0 documents as informational as agreed with our Area
           Director on 11/12/1998.
 3.1.2,    Clarify that the IPP object SHOULD NOT validate the
 16.3.3    range of the request-id being 1 to 2**31-1, but accepts
 [now ipp- and returns any value.  Clients MUST still keep in the
 iig]      range 1 to 2**31 though.  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  (Issue 1.36).
 3.1.4.1,  Clarified that when a client submits a request in a
 13.1.4.14 charset that is not supported, the IPP object SHOULD
           return any 'text' or 'name' attributes in the 'utf-8'
           charset, if it returns any, since clients and IPP
           objects MUST support 'utf-8'.  (Issue 1.19)
 3.1.4.1   Clarified Section 3.1.4.1 Request Operation Attributes
           that a client MAY use the attribute level natural
           language override (text/nameWithLanguage) redundantly in
           a request.  (Issue 1.46)
 3.1.4.2   Clarified Section 3.1.4.2 Response Operation Attributes
           that an IPP object MAY use the attribute level natural
           language override (text/nameWithLanguage) redundantly in
           a response.  (Issue 1.46)

deBry, et al. Experimental [Page 168] RFC 2566 IPP/1.0: Model and Semantics April 1999

 3.1.6     Clarified section 3.1.6:  If the Printer object supports
           the "status-message" operation attribute, it NEED NOT
           return a status message for the following error status
           codes:  'client-error-bad-request', 'client-error-
           charset-not-supported', 'server-error-internal-error',
           'server-error-operation-not-supported', and 'server-
           error-version-not-supported'.
 3.2.1.1   Clarified that if a client is not supplying any Job
           Template attributes in a request, the client SHOULD omit
           Group 2 rather than sending an empty group.  However, a
           Printer object MUST be able to accept an empty group.
           This makes [RFC2566] agree with [RFC2565].  (Issue 1.16)
 3.2.1.2,  Clarified that if an IPP object is not returning any
 3.2.5.2,  Unsupported Attributes in a response, the IPP object
 3.2.6.2,  SHOULD omit Group 2 rather than sending an empty group.
 3.3.1.2,  However, a client MUST be able to accept an empty group.
 3.3.3.2,  This makes [RFC2566] agree with [RFC2565].  (Issue 1.17)
 3.3.4.2
 3.2.1.2,  Clarified that an IPP object MUST treat an unsupported
 13.1.2.2, attribute syntax supplied in a request in the same way
 13.1.4.12 as an unsupported value.  The IPP object MUST return the
           attribute, the attribute syntax, and the value in the
           Unsupported Attributes group.  (Issue 1.26)
 3.2.5.2,  Clarified for Get-Printer-Attributes, Get-Jobs, and Get-
 3.2.6.2,  Job-Attributes that an IPP object MUST return
 3.3.4.2,  'successful-ok-ignored-or-substituted-attributes' (0x1),
 13.1.2.1, rather than 'successful-ok' (0x0), when a client
 13.1.2.2, supplies unsupported attributes as values of the
 13.1.4.12 'requested-attributes' operation attribute.  (Issue
           1.24)
           Also clarified that the response NEED NOT contain the
           "requested-attributes" operation attribute with any
           supplied values (attribute keywords) that were requested
           by the client but are not supported by the IPP object.
           (Issue 1.18)
 3.2.6.2   Deleted the job-level natural language override (NLO)
 4.1.1.2   from Section 3.2.6.2 Get-Jobs Response so that all
 4.3.24    operation responses are the same with respect to NLO.
           (Issue 1.47)

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 3.3.1     Clarified that an IPP Printer that supports the Create-
           Job operation MUST handle the situation when a client
           does not supply Send-Document or Send-URI operations
           within a one- to four-minute time period.  Also
           clarified that a client MUST send documents in a multi-
           document job without undue or unbounded delay.  (Issue
           1.28)
 3.3.3     Clarified that the IPP object MUST reject a Cancel-Job
           request if the job is in 'completed', 'canceled', or
           'aborted' job states.  (Issue 1.12)
 4.1.2.3   Added this new sub-section:  it specifies that
           nameWithoutLanguage plus the implicit natural language
           matches nameWithLanguage, if the values and natural
           languages are the same.  Also added that keyword never
           matches nameWithLanguage or nameWithoutLanguage.
           Clarified that if both have countries, that the
           countries SHOULD match as well.  If either do not, then
           the country field SHOULD be ignored.  (Issues 1.33 and
           1.34)
 4.1.5     Clarified regarding the case-insensitivity of URLs to
           refer only to the RFCs that define them.  (Issue 1.10)
 4.1.11    Clarified that 'boolean' is not a full-sized integer.
           (Issue 1.38)
 4.1.15    Clarified that 'resolution' is not three full-sized
           integers.  (Issue 1.20)
 4.2.*     Clarified that standard values are keywords or enums,
           not names.  (Issue 1.49).
 4.2.4     Added the 'single-document-new-sheet' value to Section
           4.2.4 multiple-document-handling.  (Issue 1.54)
 4.4.18,   Clarified that the "document-format-default" and
 4.4.19    "document-format-supported" Printer Description
           attributes are REQUIRED to agree with the table.  (Issue
           1.4)
 4.4.21    Changed "queued-job-count" from OPTIONAL to RECOMMENDED.
           (Issue 1.14)

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 4.4.28    Clarified that the implementation supplied value for the
           "multiple-operation-time-out" attribute SHOULD be
           between 30 and 240 seconds, though the implementation
           MAY allow the administrator to set values, and MAY allow
           values outside this range.  (Issue 1.28)
 5.1,      Clarified Client Conformance that if a client supports
 5.2.5     an attribute of 'text' attribute syntax, that it MUST
           support both the textWithoutLanguage and the
           textWithLanguage forms.  Same for 'name' attribute
           syntax.  Same for an IPP object (Issue 1.48)
 6.5,      Added new section to allow Attribute Groups to be
 12.8      registered as extensions for being passed in operation
           requests and responses.  (Issue 1.25)
 7.        Updated the table of text and name attributes to agree
           with Section 4.2.
 8.5       Added a new section RECOMMENDING that the Get-Jobs
           SHOULD return non-IPP jobs whether or not assigning them
           a job-id and job-uri.  Also RECOMMENDED generating, if
           possible, job-id and job-uri and supporting other IPP
           operations on foreign jobs as an implementer option.
           (Issue 1.32)
 9.        Updated document references.
 13.1.4.14 Clarified 'client-error-charset-not-supported' that
           'utf-8' must be used for any 'text' or 'name' attributes
           returned in the error response (Issue 1.19).
 13.1.5.9  Added a new error code 'server-error-job-canceled'
           (0x0508) to be returned if a job is canceled by another
           client or aborted by the IPP object while the first
           client is still sending the document data.  (Issue 1.29)
 15.3,     Moved these sections recommending operation processing
 15.4      steps to the new Implementer's Guide (informational).
           There indicated that all of the error checks are not
           required, so an IPP object MAY be forgiving and accept
           non-conforming requests.  However, a conforming client
           MUST supply requests that would pass all of the error
           checks indicated.  (Issue 1.21)

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 16        Changed directory schema attributes from REQUIRED to
           RECOMMENDED.  Changed some of the OPTIONAL to
           RECOMMENDED to agree with the SLP template.  Changed the
           "charset-supported" and "natural-language-supported"
           from REQUIRED to OPTIONAL.  Recommended that the names
           be the same in a directory entry as the IPP attribute
           names. (Issue 1.53)

deBry, et al. Experimental [Page 172] RFC 2566 IPP/1.0: Model and Semantics April 1999

18. Full Copyright Statement

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deBry, et al. Experimental [Page 173]

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