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rfc:rfc6075

Internet Engineering Task Force (IETF) D. Cridland Request for Comments: 6075 Isode Limited Updates: 2244 December 2010 Category: Standards Track ISSN: 2070-1721

The Internet Assigned Number Authority (IANA) Application Configuration

          Access Protocol (ACAP) Vendor Subtrees Registry

Abstract

 The original Application Configuration Access Protocol (ACAP)
 specification included a vendor registry now used in other protocols.
 This document updates the description of this registry, removing the
 need for a direct normative reference to ACAP and removing ambiguity.

Status of This Memo

 This is an Internet Standards Track document.
 This document is a product of the Internet Engineering Task Force
 (IETF).  It represents the consensus of the IETF community.  It has
 received public review and has been approved for publication by the
 Internet Engineering Steering Group (IESG).  Further information on
 Internet Standards is available in Section 2 of RFC 5741.
 Information about the current status of this document, any errata,
 and how to provide feedback on it may be obtained at
 http://www.rfc-editor.org/info/rfc6075.

Copyright Notice

 Copyright (c) 2010 IETF Trust and the persons identified as the
 document authors.  All rights reserved.
 This document is subject to BCP 78 and the IETF Trust's Legal
 Provisions Relating to IETF Documents
 (http://trustee.ietf.org/license-info) in effect on the date of
 publication of this document.  Please review these documents
 carefully, as they describe your rights and restrictions with respect
 to this document.  Code Components extracted from this document must
 include Simplified BSD License text as described in Section 4.e of
 the Trust Legal Provisions and are provided without warranty as
 described in the Simplified BSD License.

Cridland Standards Track [Page 1] RFC 6075 ACAP Vendor Subtrees Registry December 2010

Table of Contents

 1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 2
 2.  Conventions Used in This Document . . . . . . . . . . . . . . . 2
 3.  The Vendor Subtree Registry . . . . . . . . . . . . . . . . . . 3
   3.1.  Internationalization  . . . . . . . . . . . . . . . . . . . 3
   3.2.  Formal Syntax . . . . . . . . . . . . . . . . . . . . . . . 4
   3.3.  Examples  . . . . . . . . . . . . . . . . . . . . . . . . . 4
   3.4.  Changes from RFC 2244 . . . . . . . . . . . . . . . . . . . 5
 4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5
   4.1.  Example Registration  . . . . . . . . . . . . . . . . . . . 6
 5.  Security Considerations . . . . . . . . . . . . . . . . . . . . 6
 6.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . 6
 7.  References  . . . . . . . . . . . . . . . . . . . . . . . . . . 6
   7.1.  Normative References  . . . . . . . . . . . . . . . . . . . 6
   7.2.  Informative References  . . . . . . . . . . . . . . . . . . 7

1. Introduction

 The [ACAP] specification includes the specification and creation of
 the ACAP Vendor Registry, and this registry has subsequently been
 reused by several specifications, including both [ANNOTATE] and
 [METADATA], and is proving to be a useful mechanism for namespacing
 various names to within a specific vendor's scope.
 The use of textual rather than numeric identifiers for vendors
 benefits engineers and operators who are diagnosing protocol problems
 by allowing them some possibility of identifying the origin of a
 vendor attribute without having to look it up in a registry (although
 that remains a necessary fallback).  As such, engineers and operators
 already have to be familiar with international technical English to
 diagnose textual protocol problems, the restriction to ASCII may help
 and is not believed to harm that intended use.  Exposure of vendor
 attributes directly in end-user user interfaces was not an intended
 use of the registry.
 This document merely updates the registry to reduce ambiguity in the
 original specification and dissociates it from the original document
 in all but name, allowing easier referencing.  It replaces Section
 7.4 and portions of Section 4, particularly Section 4.3, of [ACAP].

2. Conventions Used in This Document

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

Cridland Standards Track [Page 2] RFC 6075 ACAP Vendor Subtrees Registry December 2010

 The formal syntax is to be considered normative and is specified
 using [ABNF].  Where a formal syntax and the prose are in conflict,
 the formal syntax takes precedence.

3. The Vendor Subtree Registry

 A Vendor Token is a UTF-8 string that begins with "vendor." and that
 is followed by the name of the company or product.  This name MUST
 NOT contain any slash character, period, or the percent and asterisk
 characters typically used as wildcards.
 Following this may be names, separated from the Vendor Token by a
 period, which need not be registered, thus forming a complete Vendor
 Name.

3.1. Internationalization

 Vendor Tokens are able to contain any valid Unicode codepoint,
 encoded as [UTF-8], except the special characters.  Since the
 publication of [ACAP], however, concerns have been raised on the
 handling and comparison of full Unicode strings; therefore, this
 specification restricts the current registrations to the ASCII subset
 of UTF-8.
 Furthermore, characters such as ASCII control characters, most
 whitespace, and quotes are likely to be confusing and have been
 similarly restricted.
 Therefore, this document allows only ASCII letters, digits, the
 hyphen, and space to be used in registrations (the <iana-vendor-tag>
 ABNF production in Section 3.2).
 At the time of publication of this document, no existing
 registrations violate the new restricted syntax on characters allowed
 in registrations.  [ACAP] required all Vendor Tokens to be registered
 with IANA, so the new restriction is not believed to introduce any
 interoperability issue.
 Finally, note that this document does not change the requirement on
 processors to accept other non-ASCII Unicode codepoints in Vendor
 Tokens (the <possible-vendor-tag> ABNF production in Section 3.2).

Cridland Standards Track [Page 3] RFC 6075 ACAP Vendor Subtrees Registry December 2010

3.2. Formal Syntax

 This syntax draws upon productions found within [ABNF] and [UTF-8].
 Productions replace those in Section 4.3 of [ACAP].
 vendor-name         = vendor-token *("." name-component)
 name-component      = *(name-char / UTF8-2 / UTF8-3 / UTF8-4)
 name-char           = %x01-24 / %x26-29 / %x2B-2D / %x30-7F
                   ;; ASCII-range characters not including ".",
                   ;; "/", "%", or "*".
 vendor-token        = "vendor." vendor-tag
                   ;; MUST be registered with IANA
 vendor-tag          = iana-vendor-tag / possible-vendor-tag
 iana-vendor-tag     = 1*(ALPHA / DIGIT / SP / "-")
                   ;; This production represents
                   ;; allowed forms for registrations
                   ;; under the rules specified in this
                   ;; document.
 possible-vendor-tag = name-component
                   ;; This production represents what
                   ;; applications and specifications
                   ;; MUST be able to accept.

3.3. Examples

 A company Example, Ltd. might register the Subtree "vendor.example".
 This means it may use "vendor.example", or any name at all beginning
 "vendor.example.", such as "vendor.example.product".
 These names might be used in several protocols, and are reserved in
 all the relevant protocols, so "vendor.example" might be an ACAP
 [ACAP] dataset class name, and "/vendor/vendor.example" might be a
 tree of IMAP ANNOTATE entries [ANNOTATE].
 Example, Ltd. is free to use either "vendor.example", and group
 specific products under it using the relevant protocol's hierarchy --
 perhaps "/shared/vendor/vendor.example/product" annotation
 [ANNOTATE], or using more specific names, such as "/shared/vendor/
 vendor.example.product" annotation.
 Note that the solidus ("/") characters in the examples above are
 protocol delimiters that are themselves not part of the Vendor Token.

Cridland Standards Track [Page 4] RFC 6075 ACAP Vendor Subtrees Registry December 2010

3.4. Changes from RFC 2244

 This non-normative section details changes from the original
 specification of the registry in RFC 2244.
 o  Vendor Tokens are restricted to ASCII for registration purposes.
 o  Clarifications that "vendor.<company/product name>" means
    "vendor.company name" or "vendor.product name" - "vendor.company/
    product" is and always has been illegal.
 o  Made "vendor.company" a name in its own right - RFC 2244 only
    refers to a prefix of "vendor.company.".
 o  Added example registration, in line with [EXAMPLES].

4. IANA Considerations

 This specification updates the IANA registry named the ACAP "Vendor
 Subtrees" registry.  IANA has updated the registry to point at this
 document.
 Vendors may reserve a portion of the ACAP namespace, which is also
 used as the namespace for several other protocols, for private use.
 Vendor Names are reserved for use by that company or product,
 wherever used, once registered.  Registration is on a first come,
 first served basis.  Whenever possible, private attributes and
 classes should be eschewed in favour of improving interoperable
 protocols.
 Vendors may only use names conforming to iana-vendor-tag at the
 current time; future revisions of this specification may change this.
 To: iana@iana.org
 Subject: Registration of ACAP Vendor Subtree
 Private Prefix: vendor.name
 Person and email address to contact for further information:
 (company names and addresses should be included where appropriate)

Cridland Standards Track [Page 5] RFC 6075 ACAP Vendor Subtrees Registry December 2010

4.1. Example Registration

 IANA is requested to add the following registration, for use by
 specification authors in examples, similarly to the domains specified
 in [EXAMPLES]:
 To: iana@iana.org
 Subject: Registration of ACAP Vendor Subtree
 Private Prefix: vendor.example
 Person and email address to contact for further information:
 Dave Cridland <dave.cridland@isode.com>

5. Security Considerations

 There are no known security issues with this registry.  Individual
 protocols using Vendor Subtree names may have security issues, and
 the introduction of Unicode has, in itself, security implications --
 the restriction of this is thought to mitigate these.

6. Acknowledgements

 Thanks must go to Chris Newman, John Myers, and the other designers
 of ACAP for the initial creation of the registry.  Thanks also to
 Alexey Melnikov for advice on this revision.

7. References

7.1. Normative References

 [ABNF]     Crocker, D. and P. Overell, "Augmented BNF for Syntax
            Specifications: ABNF", STD 68, RFC 5234, January 2008.
 [ACAP]     Newman, C. and J. Myers, "ACAP -- Application
            Configuration Access Protocol", RFC 2244, November 1997.
 [KEYWORDS]
            Bradner, S., "Key words for use in RFCs to Indicate
            Requirement Levels", BCP 14, RFC 2119, March 1997.
 [UTF-8]    Yergeau, F., "UTF-8, a transformation format of ISO
            10646", STD 63, RFC 3629, November 2003.

Cridland Standards Track [Page 6] RFC 6075 ACAP Vendor Subtrees Registry December 2010

7.2. Informative References

 [ANNOTATE]
            Daboo, C. and R. Gellens, "Internet Message Access
            Protocol - ANNOTATE Extension", RFC 5257, June 2008.
 [EXAMPLES]
            Eastlake 3rd, D. and A. Panitz, "Reserved Top Level DNS
            Names", BCP 32, RFC 2606, June 1999.
 [METADATA]
            Daboo, C., "The IMAP METADATA Extension", RFC 5464,
            February 2009.

Author's Address

 Dave Cridland
 Isode Limited
 5 Castle Business Village
 36, Station Road
 Hampton, Middlesex  TW12 2BX
 GB
 EMail: dave.cridland@isode.com

Cridland Standards Track [Page 7]

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