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rfc:rfc3553

Network Working Group M. Mealling Request for Comments: 3553 VeriSign BCP: 73 L. Masinter Category: Best Current Practice Adobe Systems

                                                             T. Hardie
                                                              Qualcomm
                                                              G. Klyne
                                                          Nine by Nine
                                                             June 2003
    An IETF URN Sub-namespace for Registered Protocol Parameters

Status of this Memo

 This document specifies an Internet Best Current Practices for the
 Internet Community, and requests discussion and suggestions for
 improvements.  Distribution of this memo is unlimited.

Copyright Notice

 Copyright (C) The Internet Society (2003).  All Rights Reserved.

Abstract

 This document describes a new sub-delegation for the 'ietf' URN
 namespace for registered protocol items.  The 'ietf' URN namespace is
 defined in RFC 2648 as a root for persistent URIs that refer to
 IETF-defined resources.

1. Introduction

 From time to time IETF standards require the registration of various
 protocol elements in well known central repository.  The Internet
 Assigned Numbers Authority maintains this central repository and
 takes direction from the IETF on what, how and when to add items to
 it.  The IANA maintains lists of items such as all assigned port
 numbers, MIME media types, enterprise numbers, etc.
 Over time there has developed a need to be able to reference these
 elements as URIs in various schema.  In the past this was done in a
 very ad hoc way that easily led to interoperability problems.  This
 document creates a new sub-delegation below the "ietf" [2]URN
 namespace [1] called 'params' which acts as a standardized mechanism
 for naming the items registered for IETF standards.  Any assignments
 below that are specified in an RFC according to the IETF consensus
 process and which include the template found in Section 4.

Mealling, et. al. Best Current Practice [Page 1] RFC 3553 IANA URN Namespace June 2003

2. Terminology

 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 RFC 2119.

3. IETF Sub-namespace Specifics

 Sub-namespace name:
    params
 Declared registrant of the namespace:
    The Internet Engineering Task Force
 Declaration of structure:
    The namespace is primarily opaque.  The IANA, as operator of the
    registry, may take suggestions for names to assign but they
    reserve the right to assign whatever name they desire, within
    guidelines set by the IESG.  The colon character (":") is used to
    denote a very limited concept of hierarchy.  If a colon is present
    then the items on both sides of it are valid names.  In general,
    if a name has a colon then the item on the left hand side
    represents a class of those items that would contain other items
    of that class.  For example, a name can be assigned to the entire
    list of DNS resource record type codes as well as for each
    individual code.  The URN for the list might look like this:
          urn:ietf:params:dns:rr-type-codes
    while the URN for the SOA records type code might look like this:
          urn:ietf:params:dns:rr-type-codes:soa
 Relevant ancillary documentation:
    [3], [2], [1]
 Identifier uniqueness considerations:
    The IESG uses the IETF consensus process to ensure that
    sub-namespaces generate unique names within that
    sub-namespace.  The IESG delegates to the IANA the task of
    ensuring that the sub-namespace names themselves are unique.
    Until and unless the IESG specifies differently, the IANA is
    directed to ensure uniqueness by comparing the name to be assigned

Mealling, et. al. Best Current Practice [Page 2] RFC 3553 IANA URN Namespace June 2003

    with the list of previously assigned names.  In the case of a
    conflict the IANA is to request a new string from the registrant
    until the conflict is resolved.
 Identifier persistence considerations:
    Once a name has been allocated it MUST NOT be re-allocated for a
    different purpose.  The rules provided for assignments of values
    within a sub-namespace MUST be constructed so that the meaning of
    values cannot change.  This registration mechanism is not
    appropriate for naming values whose meaning may change over time.
    If a value that changes over time the assignment MUST name the
    container or concept that contains the value, not the value
    itself.  For example, if a parameter called 'foo' has a value that
    changes over time, it is valid to create the name
    'urn:ietf:params:foo-params:foo' that identifies that 'slot'.  It
    is not valid to actually create a name that contains that value
    unless it is a persistent and unique value such as a version
    number.
 Process of identifier assignment:
    Identifiers are assigned only after a particular protocol element
    or number has been registered with the IANA using standard
    policies and procedures, or documented in an RFC describing a
    standards track protocol.  This means that the 'gating' function
    for assignment is the "IETF Consensus" process documented in RFC
    2434 [4].
 Process of identifier resolution:
    At this time no resolution mechanism is defined.
 Rules for Lexical Equivalence:
    Lexical equivalence is achieved by exact string match according to
    the rules for URN syntax found in RFC 2141 [1].  Specifically, due
    to the URN syntax definitions, the 'stringprep' standard found in
    RFC 3454 [7] does not apply.
 Conformance with URN Syntax:
    There are no additional characters reserved.
 Validation mechanism:
    None.

Mealling, et. al. Best Current Practice [Page 3] RFC 3553 IANA URN Namespace June 2003

 Scope:
    Global

4. Assigning Names

 The creation of a new registry name will be simple for most flat
 registries.  The only required elements will be the registry name, a
 reference to relevant documents, a statement about which
 current/proposed document repositories contains the authoritative
 data for the registry, and a statement specifying which element in
 the registry is the value to be used in the URN.  In most cases this
 last element will be the index value assigned by the IANA.
 More complex registries (DNS Parameters for example) will need to
 repeat that information for any sub-namespaces.  It should also be
 clear as to whether or not a name is assigned to the sub-namespace
 itself (i.e., is 'urn:ietf:params:dns:rr-types' valid by itself and
 if so, what does it name?).
 The template:
 Registry name: -- The name of the sub-namespace.  In many cases this
    should be the same name that the IANA calls the registry itself.
 Specification: -- Relevant IETF published documents that define the
    registry and the items in it.
 Repository: -- A pointer to the 'current' location of the registry in
    the protocol parameters repository or the relevant RFCs that
    document the items being named.  This value will change over time
    as the entity that maintains the repository moves files and or
    fileservers.  It is not meant as a permanent binding to the
    filename but as a hint to the IANA for what the initial mapping
    would be.
 Index value: -- Description of how a registered value is to be
    embedded in the URI form.  This MUST include details of any
    transformations that may be needed for the resulting string to
    conform to URN syntax rules and any canonicalization needed so
    that the case-sensitive string comparison yields the expected
    equivalences.
 The process for requesting that a URN be assigned is currently to put
 the above template or a reference to it in the IANA considerations
 section of the specifying document.  Other more automated processes
 may be proposed at a latter time if demand requires it.

Mealling, et. al. Best Current Practice [Page 4] RFC 3553 IANA URN Namespace June 2003

5. Security Considerations

 None not already inherent to using URNs.  Security considerations for
 URNs in general can be found in RFC 2141 [1].  Further security
 considerations for one specific URN resolution method can be found in
 Dynamic Delegation  Discovery System (DDDS) Part Four: The Uniform
 Resource Identifiers (URI) Resolution Application (RFC 3404) [5]
 which is part of a series starting with Dynamic  Delegation Discovery
 System (DDDS) Part One: The Comprehensive DDDS  (RFC 3401) [6].

6. IANA Considerations

 This document puts a new and significant burden on the IANA since it
 may require an additional assignment process to happen for each new
 IANA registry.  To minimize the administrative burden on IANA, any
 parameter namespace registration is very clear about the criteria for
 inclusion in that namespace.
 Defining a registry that fits the constraints of a URN namespace will
 impose extra discipline that should take some of the guess-work about
 creating and maintaining that registry.

7. Intellectual Property Statement

 The IETF takes no position regarding the validity or scope of any
 intellectual property or other rights that might be claimed to
 pertain to the implementation or use of the technology described in
 this document or the extent to which any license under such rights
 might or might not be available; neither does it represent that it
 has made any effort to identify any such rights.  Information on the
 IETF's procedures with respect to rights in standards-track and
 standards-related documentation can be found in BCP-11.  Copies of
 claims of rights made available for publication and any assurances of
 licenses to be made available, or the result of an attempt made to
 obtain a general license or permission for the use of such
 proprietary rights by implementors or users of this specification can
 be obtained from the IETF Secretariat.
 The IETF invites any interested party to bring to its attention any
 copyrights, patents or patent applications, or other proprietary
 rights which may cover technology that may be required to practice
 this standard.  Please address the information to the IETF Executive
 Director.

Mealling, et. al. Best Current Practice [Page 5] RFC 3553 IANA URN Namespace June 2003

8. Normative References

 [1]  Moats, R., "URN Syntax", RFC 2141, May 1997.
 [2]  Moats, R., "A URN Namespace for IETF Documents", RFC 2648,
      August 1999.
 [3]  Daigle, L., van Gulik, D., Iannella, R. and P. Faltstrom,
      "Uniform Resource Names (URN) Namespace Definition Mechanisms",
      BCP 66, RFC 3406, October 2002.
 [4]  Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA
      Considerations Section in RFCs", BCP 26, RFC 2434, October 1998.
 [5]  Mealling, M., "Dynamic Delegation Discovery System (DDDS) Part
      Four: The Uniform Resource Identifiers (URI)", RFC 3404,
      February 2002.
 [6]  Mealling, M., "Dynamic Delegation Discovery System (DDDS) Part
      One: The Comprehensive DDDS", RFC 3401, May 2002.
 [7]  Hoffman, P. and M. Blanchet, "Preparation of Internationalized
      Strings ("stringprep")", RFC 3454, December 2002.

Mealling, et. al. Best Current Practice [Page 6] RFC 3553 IANA URN Namespace June 2003

9. Authors' Addresses

 Michael Mealling
 VeriSign
 21345 Ridgetop Circle
 Sterling, VA  20166
 US
 EMail: michael@verisignlabs.com, michael@neonym.net
 URI:   http://www.verisign.com
 Larry Masinter
 Adobe Systems Incorporated
 345 Park Ave
 San Jose, CA  95110
 US
 Phone: +1 408 536-3024
 EMail: LMM@acm.org
 URI:   http://larry.masinter.net
 Ted Hardie
 Qualcomm, Inc.
 675 Campbell Technology Parkway
 Suite 200
 Campbell, CA
 U.S.A.
 EMail: hardie@qualcomm.com
 Graham Klyne
 Nine by Nine
 EMail: GK-IETF@ninebynine.org
 URI:   http://www.ninebynine.net/

Mealling, et. al. Best Current Practice [Page 7] RFC 3553 IANA URN Namespace June 2003

10. Full Copyright Statement

 Copyright (C) The Internet Society (2003).  All Rights Reserved.
 This document and translations of it may be copied and furnished to
 others, and derivative works that comment on or otherwise explain it
 or assist in its implementation may be prepared, copied, published
 and distributed, in whole or in part, without restriction of any
 kind, provided that the above copyright notice and this paragraph are
 included on all such copies and derivative works.  However, this
 document itself may not be modified in any way, such as by removing
 the copyright notice or references to the Internet Society or other
 Internet organizations, except as needed for the purpose of
 developing Internet standards in which case the procedures for
 copyrights defined in the Internet Standards process must be
 followed, or as required to translate it into languages other than
 English.
 The limited permissions granted above are perpetual and will not be
 revoked by the Internet Society or its successors or assigns.
 This document and the information contained herein is provided on an
 "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
 TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
 BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
 HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
 MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

Acknowledgement

 Funding for the RFC Editor function is currently provided by the
 Internet Society.

Mealling, et. al. Best Current Practice [Page 8]

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