IETF URNbis WG                                                 A. Hoenes
Internet-Draft                                                    TR-Sys
Obsoletes: 3406 (if approved)                           October 31, 2011                             March 12, 2012
Intended status: BCP
Expires: May 3, September 13, 2012

      Uniform Resource Name (URN) Namespace Definition Mechanisms


   Uniform Resource Names (URNs) are intended to serve as persistent,
   location-independent, resource identifiers.  To structure and
   organize their usage, the URN syntax (RFC 2141bis) specifies a
   hierarchy that divides the set of possible URNs into "URN Namespaces"
   that can be individually defined and managed.  URN Namespaces in
   particular serve to map existing identifier systems into the URN
   system and thereby make available generic, network-based resolution
   services for the identified documents, artifacts, and other objects
   (and their
   metadata). metadata related to them).

   To actually leverage such synergetic advantage, achive these goals, URN Namespaces need to be specified in a
   comparable manner, and their Namespace Identifiers (NIDs) need to be
   registered with IANA, so that naming conflicts are avoided and
   implementers of services can follow a structured approach in support
   of various namespaces, guided by the registry to the related
   documents and the particularities of specific namespaces, as
   described in these namespace Namespace registration documents.

   This document RFC serves as a guideline for authors of URN Namespace
   definition and registration documents. documents and the process to be followed
   to register a URN Namespace with IANA.  It describes the essential
   content of such documents and how they shall be structured to allow
   readers familar with the scheme to quickly assess the properties of a
   specific URN Namespace.  Further, this RFC describes the process to
   be followed to get a URN Namespace registered with IANA.

   This document is a companion document to the revised URN Syntax
   specification, RFC 2141bis; it supersedes and replaces RFC 3406.


   Discussion of this memo utilizes the mailing list.

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   This Internet-Draft will expire on May 3, September 13, 2012.

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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
     1.1.  Requirement Language . . . . . . . . and Terminology . . . . . . . . . . .  5
   2.  What is a URN Namespace? . . . . . . . . . . . . . . . . . . .  5
   3.  URN Namespace (Registration) Types . . . . . . . . . . . . . .  6  7
     3.1.  Experimental Namespaces  . . . . . . . . . . . . . . . . .  6  7
     3.2.  Informal Namespaces  . . . . . . . . . . . . . . . . . . .  6  7
     3.3.  Formal Namespaces  . . . . . . . . . . . . . . . . . . . .  7
   4.  URN Namespace Registry: Processes for Registration and
       Update . . . . . . . . . . . . . . . . . . . . . . . . . . . .  8  9
     4.1.  Experimental Namespaces: No Registration . . . . . . . . .  9 10
     4.2.  Informal Namespaces  . . . . . . . . . . . . . . . . . . .  9 10
     4.3.  Formal Namespaces  . . . . . . . . . . . . . . . . . . . . 10 11
     4.4.  Registration Documents . . . . . . . . . . . . . . . . . . 11 12
       4.4.1.  Namespace Considerations in Registration Documents . . 11 12
       4.4.2.  Community Considerations in Registration Documents . . 12 13
       4.4.3.  Security Considerations in Registration Documents  . . 12 14
       4.4.4.  IANA Considerations in Registration Documents  . . . . 13 14
   5.  Security Considerations  . . . . . . . . . . . . . . . . . . . 14 15
   6.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 14 15
   7.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 15 16
   8.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 15 17
     8.1.  Normative References . . . . . . . . . . . . . . . . . . . 15 17
     8.2.  Informative References . . . . . . . . . . . . . . . . . . 15 17
   Appendix A.  URN Namespace Definition Template . . . . . . . . . . 16 18
   Appendix B.  Illustration  . . . . . . . . . . . . . . . . . . . . 22
     B.1.  Example Template . . . . . . . . . . . . . . . . . . . . . 22
     B.2.  Registration steps in practice  . . . . . . . . . . . . . . 24
   Appendix C.  Changes from RFC 3406 . . . . . . . . . . . . . . . . 25
     C.1.  Essential Changes since RFC 3406 . . . . . . . . . . . . . 25
     C.2.  Changes from RFC 3406 to URNbis WG Draft -00 . . . . . . . 25
   Appendix D.  Open Issues
     C.3.  Changes from URNBIS WG I-D -00 to -01  . . . . . . . . . . 28
     C.4.  Changes from URNBIS WG I-D -01 to -02  . . . . . . . . . . 28
   Appendix D.  Issues in this Draft  . . . . . . . . . . . . . . . . 28

1.  Introduction

   Uniform Resource Names (URNs) are resource identifiers with adhering to
   the specific requirements for of enabling location-independent
   identification of a resource, as well as longevity of reference.
   URNs are part of the larger Uniform Resource Identifier (URI) family
   (see the joint W3C/IETF memorandum, RFC 3305 [RFC3305], and the IETF
   STD 66, RFC 3986 [RFC3986]) with the specific goal of providing
   persistent naming of resources.

   The URN Syntax (see below and RFC 2141bis
   [I-D.ietf-urnbis-rfc2141bis-urn]) structures and organizes the
   entirety of URNs into a hierarchy that divides the set of possible
   URNs into "URN Namespaces" that can be individually defined, managed,
   and (optionally) further subdivided.  URN Namespaces in particular
   serve to map existing identifier systems into the URN system and
   thereby make available generic, network-based resolution services for
   the identified documents, artifacts, and other objects (and their

   There are two assumptions that are key to this document:

   Assumption #1:  Assignment of a URN is a managed process.

      I.e., not all strings that conform to URN syntax are necessarily
      valid URNs.  A URN is assigned according to the rules of a
      particular namespace (in terms of syntax, semantics, and process).

   Assumption #2:  The space of URN Namespaces is managed.

      I.e., not all syntactically correct URN Namespaces (per the URN
      syntax definition) are valid URN Namespaces.  A URN Namespace must
      have a recognized definition in order to be valid.

   The purpose of this document is to

   To actually leverage the potential synergetic advantage of this
   unification (structured embedding of existing namespaces into the URN
   framework), URN Namespaces need to be specified in a comparable
   manner, and their Namespace Identifiers (NIDs) need to be centrally
   registered, so that naming conflicts are avoided and implementers of
   services can follow a structured approach in support of various
   namespaces, guided by the registry to the related documents and the
   particularities of specific namespaces, as described in these
   Namespace registration documents.

   The purpose of this document is to outline a mechanism and provide a
   template for explicit namespace URN Namespace definition, as well as provide
   the mechanism for associating an identifier (called a "Namespace ID",
   or NID), which is registered with the Internet Assigned Numbers
   Authority (IANA) [IANA] in the URN Namespaces registry maintained at

   The URN Namespace definition and registration mechanisms originally
   have been specified in RFC 2611 [RFC2611], which has been obsoleted
   by BCP 66, RFC 3406 [RFC3406].  Guidelines for documents prescribing
   IANA procedures have been revised as well over the years, and at the
   time of this writing, BCP 26, RFC 5226 [RFC5226] is the normative
   document.  This document is a revision of RFC 3406 based on the
   revised URN Syntax specification RFC 2141bis
   [I-D.ietf-urnbis-rfc2141bis-urn] and RFC 5226.

   The reader is referred to Section 1.1 of RFC 2141bis
   [I-D.ietf-urnbis-rfc2141bis-urn] for a more detailed synopsis of the
   history of documents fundamental for URNs.

   Note that this document restricts itself to the description of
   processes for the creation of URN Namespaces.  If generic
   "resolution" of any so-created URN identifiers is desired, a separate
   process of registration in a global NID directory, such as that
   proposed by the DDDS system [RFC3401], is necessary.  See [RFC3405]
   for information on obtaining registration in the DDDS global NID
   directory.  There also is work in progress [Ref: t.b.d.] to establish
   an IANA registry for URN services, such that registration documents
   can unambiguously identify such services and discuss their
   applicability to the particular URN Namespace.

1.1.  Requirement Language and Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   document are to be interpreted as described in RFC 2119 [RFC2119].
   In this document, these key words describe requirements for the
   process to be followed and the content to be provided in namespace URN
   Namespace definition documents and registration templates.

   For the purpose of this document, its subject is spelled "URN
   Namespace" (in headline case), whereas in other context, "namespace"
   is spelled in lowercase, lower case, e.g. to designate a (standard or non-
   standard) identifier system on which a URN Namespace is based.

2.  What is a URN Namespace?

   For the purposes of URNs, a "namespace" is a collection of uniquely-
   assigned identifiers.  That is, the identifiers are not ever assigned
   to more than 1 one resource.  These resources may be stable (e.g., a
   doctoral dissertation or an abstract concept of a protocol) or
   dynamic (e.g., a continuously evolving web site of a periodical or a
   specific protocol parameter registry subject to additions and
   maintenance).  If the identified resource is a metadata record, such
   record may describe several objects (such as two versions of a book)
   or a collection of objects (such as a periodical with, say, monthly
   issues); in this case, these subordinate objects are not the
   identified resources.  For each namespace, it must be clear what the
   identified resources are; if the namespace is heterogenous in this
   respect, the registration and resolution systems must unambiguously
   designate the kind of identified resource, nor for each identifier
   assigned in the namespace.  Once assigned, URNs are they ever never re-assigned
   to a different resource.  A single resource, however, may have more
   than one URN assigned to it -- within a particular Namespace or among
   different Namespaces -- for different purposes. purposes, since the Namespaces
   are not mutually exclusive.

   Such abstract namespace might be defined by some pre-established
   (standard or non-standard) identifier system that can be made
   "network-actionable" by embedding it into the URN framework using a
   specific URN Namespace.  A URN Namespace itself has an identifier in
   order to:

   -  ensure global uniqueness of URNs,

   -  (where desired) provide a cue for the structure of the identifier.

   For example, many identifier systems use strings of numbers as
   identifiers (e.g., ISBN, ISSN, phone numbers).  It is conceivable
   that there might be some numbers that are valid identifiers in two
   different established identifier systems.  Using different
   designators for the two collections (and making these designators an
   intrinsic syntactic part of URNs) ensures that no two URNs will be
   the same for different resources (since each collection is required
   to uniquely assign each identifier).

   The development of an identifier structure, and thereby a collection
   of identifiers, is a process that is inherently dependent on the
   requirements of the community defining the identifier, how they will
   be assigned, and the uses to which they will be put.  All of these
   issues are specific to the individual community seeking to define a
   namespace (e.g., publishing community, association of booksellers,
   protocol developers, technology-specific vendor groups, etc.); they
   are beyond the scope of the IETF URN work.

   This document outlines the processes by which a collection of
   identifiers satisfying certain constraints (uniqueness of assignment,
   etc.) can become a bona fide URN Namespace by obtaining a NID.  In a
   nutshell, a template for the definition of the namespace Namespace is completed
   for deposit with IANA, and a NID is assigned.  The details of the
   process and possibilities for NID strings are outlined below.

3.  URN Namespace (Registration) Types

   There are three categories (types) of URN Namespaces defined here,
   distinguished by expected level of service and required procedures
   for registration.  Registration processes for each of these namespace Namespace
   types are given in Section 4.

3.1.  Experimental Namespaces

   These are not explicitly registered with IANA.  In both this Section and Section 4
   these categories are ordered by increasing relevance/importance for
   the Internet and, accordingly, increasing strenght of requirements
   for the definition and registration processes.

3.1.  Experimental Namespaces

   These are not explicitly registered with IANA.

   No provision is made for avoiding collision of experimental NIDs;
   they are intended for use within internal or limited experimental
   contexts.  However, as described below in Section 4.1, these are
   designated by a specific form of the NID to allow differentiation
   (without preexisting knowledge of details) from the other URN
   Namespace types.

   [[ Editorial Note:
   Has anybody ever seen usage of such experimental URN Namespaces?
   According to the observations of the author, three years of RFC 2611
   and nine years of RFC 3406 have constantly seen "tentative grabbing"
   and subsequent usage of NIDs that the stakeholders later have tried
   to register with IANA as Formal NIDs (with varying success).
   So should this kind of namespaces better be dropped and a kind of
   provisional NIDs be created? -- This would be in the spirit of BCP
   100, RFC 4020 [RFC4020], and it would resemble the manner how URI
   Scheme registrations are dealt with (RFC 4395 [RFC4395], [IANA-URI]).

3.2.  Informal Namespaces

   These are fully fledged URN Namespaces, with all the rights and
   requirements associated thereto.  Informal namespaces Namespaces can be
   registered in global registration services.  They are required to
   uphold the general principles of a well-managed URN Namespace --
   providing persistent identification of resources and unique
   assignment of identifier strings.  Informal and formal namespaces Formal Namespaces
   (described below) differ in the NID assignment.  IANA will assign an
   alphanumeric to
   registered Informal Namespaces a simply structured, alphanumeric,
   ordinal NID (following a pattern defined pattern) to registered informal
   namespaces, in Section 4.2 below), per
   the process outlined in Section 4.

3.3.  Formal Namespaces

   A formal namespace Formal Namespace may be requested, and IETF review sought, in cases
   where the publication of the NID proposal and the underlying
   namespace will provide benefit to some subset of users on the
   Internet.  That is, a formal NID proposal, if accepted, must be
   functional on and with the global Internet, not limited to users in
   communities or networks not connected to the Internet.  For example,
   assume a NID is requested that is meant for naming of physics
   research material.  If that NID request required that the user use a
   proprietary network or service that was not at all open to the
   general Internet user, then it would make a poor request for a formal
   NID.  The intent is that, while the community of those who may
   actively use the names assigned within that NID may be small (but no
   less important), the potential use of names within that NID is open
   to any user on the Internet.

   It is however expected that Formal NIDs may be applied to namespaces Namespaces
   where some aspects are not fully open.  For example, a namespace Namespace may
   make use of a fee-based, privately managed, or proprietary registry
   for assignment of URNs in the namespace, Namespace, but it may still provide
   benefit to some Internet users if the services associated with it
   have openly- openly published access protocols.

   In addition to the basic registration information defined in the
   registration template (in Appendix A), a formal namespace Formal Namespace request
   must be accompanied by documented considerations of the need for a
   new namespace Namespace and of the community benefit from formally establishing
   the proposed URN Namespace.

   Additionally, since the goal of URNs is to provide persistent
   identification, some careful consideration as must be given to the longevity
   and maintainability of the namespace must be given. URN Namespace.  The collective experience
   of the IETF community contains a wealth of information on technical
   factors that will prevent longevity of identification.  Thus, the
   IESG may elect not to accept a proposed namespace Namespace registration if the
   IETF community consensus is that the registration document contains
   technical flaws that will prevent (or seriously impair the
   possibility of) persistent identification, and that it therefore
   should not be published as an RFC.

   In addition to the technical aspects of the namespace Namespace and its
   resolution, consideration should be given to the following
   organizatorial aspects:

   -  the organization maintaining the URN Namespace should credibly
      demonstrate stability and the ability to maintain the URN namespace
      Namespace for a long time, and/or it should be clear how the namespace
      Namespace can continue to be usable/useful if the organization
      ceases to be able to foster it;

   -  it  the organization(s) assigning URNs within the URN Namespace should
      demonstrate ability and competency in name assignment; this should
      improve the likelihood of persistence (e.g., to minimize the
      likelihood of conflicts);

   -  it  the organization(s) assigning URNs within the URN Namespace need
      to be committed to honor the scope, rules, and regulations
      outlined its registration document and the documents defining the
      underlying namespace and covering its identifier assignment and
      maintenance procedures (if any), and the organization maintaining
      the URN Namespace needs to have procedures in force that aim at
      ensuring this adherance at a very high confidence level; and

   -  the involved organization(s) need to commit to not re-assigning re-assign
      existing names and allowing names; old names to MUST continue to be valid, even if the
      owners or assignees of those names are no longer members or
      customers of that such organization; this does not mean that there must
      needs to be resolution of such names, but that they must not
      resolve the name such names to false or stale information, information and that they
      must not be reassigned.

   These aspects, though hard to quantify objectively, should be

   If the underlying namespace is based on an established standard, the
   standards body or the organization(s) in charge with the maintenance
   of the namespace should be involved in the process, either by
   performing the registration on their own, or by supporting the action
   of the registrant and asserting support of the registration document.

   These aspects, though hard to quantify objectively, should be
   considered by organizations/people considering the development of a
   Formal URN Namespace, and they will be kept in mind when evaluating
   the technical merits of any proposed Formal URN Namespace.  The kind
   of mandate upon which the organization aims to undertake this
   activity might give a strong indication for this evaluation, because
   it likely mirrors the trust that other parties (e.g. (for instance states,
   international treaty organizations, professionals' associations,
   etc.) put on the organization.

4.  URN Namespace Registry: Processes for Registration and Update

   Different levels of disclosure are expected/defined for namespaces. Namespaces.
   According to the level of open-forum discussion surrounding the
   disclosure, a URN Namespace may be assigned an identifier or may
   request a particular identifier.

   The IANA Considerations Guidelines document (BCP 26, RFC 5226 26 [RFC5226])
   suggests the need to specify update mechanisms for registrations --
   who is given the authority to do so, from time to time, and what are
   the processes.  Since URNs are meant to be persistently useful, few
   (if any) changes should be made to the structural interpretation of
   URN strings (e.g., adding or removing rules for lexical equivalence
   that might affect the interpretation of URN IDs already assigned).
   However, it may be important to introduce clarifications, expand the
   list of authorized URN assigners, etc., over the natural course of a namespace's
   Namespace's lifetime.  Specific processes are outlined below.

   The official list of registered URN Namespaces is currently
   maintained by IANA at
   <>. [IANA-URN].

   The registraty registry is subdivided into two sub-registries, one for "Formal
   URN Namespaces" and one for "Informal URN Namespaces", and each entry
   there links to a stable repository of the registration document or
   (an escrow copy of) the filled-out registration template.

   The registration and maintenance procedures vary slightly between the
   Namespace types.

4.1.  Experimental Namespaces: No Registration

   The NIDs of Experimental Namespaces (Section 3.1) are not explicitly
   registered with IANA.  They SHOULD take the form:


   where <nid> is a string of up to 30 characters, consisting solely of
   letters, decimal digits, and hyphen ("-") characters, as specified by
   the NID syntax specification in Section 2.1 of RFC 2141bis

   No provision is made for avoiding collision of experimental NIDs;
   they are intended for use within internal or limited experimental
   contexts exclusively.

   Note:  The above form is no more considered MANDATORY, in order to
      accommodate experience and demonstrated evidence that, under
      specific circumstances, experimental prototype systems have to
      create and assign identifiers that the interested community
      perceives are infeasible to be changed once the Namespace gets
      formally registered.  However, it is strongly RECOMMENDED to
      prefix eventually targeted NIDs by "X-" during experiments and

   As there is no registration, no registration/maintenance procedures
   are needed.

   Usage of Experimental URN Namespaces MUST be short-lived and whithin
   a private scope; it MUST NOT be disclosed to the Internet at large,
   e.g. by distribution of software versions that make use of such.

4.2.  Informal Namespaces

   The NIDs of Informal Namespaces are synthesized by the IANA using an
   assigned sequence number and registered in their own sub-registry, as
   indicated in Section 4; they take the format:


   where <number> is the decimal representation of a natural number,
   with no leading zeroes.  This sequence number is assigned by the IANA
   on a First-Come-First-Served [RFC5226] basis to registration requests
   for informal namespaces. Informal Namespaces.

   Registrants should send a copy of the registration template (as shown
   in Appendix A), duly completed, to the mailing list
   for review and allow for a two-week four-week discussion period for clarifying
   the expression of the registration information and suggestions for
   technical improvements to the namespace Namespace proposal.
   [[ Editorial NOTE: Longer An even longer time is needed in practice!  Increase  Should
   we further increase the upper limit to 4 8 weeks? ]]

   After suggestions for clarification of the registration information
   have been incorporated, the template may be submitted for assignment
   of a NID by email to .

   Registrations may be updated later by the original registrant, or by
   an entity designated by the registrant, by updating the registration
   template, submitting it to the discussion list for a further two-week four-
   week discussion period, and finally resubmitting it to IANA in a
   message to .

4.3.  Formal Namespaces

   Formal NIDs are assigned via IETF Review, as defined in BCP 26
   [RFC5226].  The designated expert(s) for URN Namespace registrations
   are nominated by the IESG, and their role adheres to the regulations
   in BCP 26, unless specified otherwise below.

   NIDs for Formal URN Namespaces MUST NOT have the forms indicated in
   the preceding two sections for the other two Namespace types.  (The
   detailed formal rules are given below in Section 4.4.4.)  Applicants,
   in concert with the IANA experts, should ensure that the sought NID
   strings are "proper" for the designated purpose, according to common
   sense (and applicable legal rules).


   "IETF Review" (per [RFC5226]) means that the Formal NID application
   is made via submission to the IETF of an Internet-Draft that contains
   the namespace Namespace definition and targets publication as an RFC of
   Informational or Standards Track Standards-Track category, which needs to be approved
   by the IESG after performing an IETF Last Call on the document and
   evaluating review comments.  The applicant can be an individual or an
   IETF working group, in alignment with the designation of the
   Internet-Draft.  It  The actual choice should be properly considered by
   applicants, but it is RECOMMENDED that the registration documents for
   NIDs belonging to an established standard namespace aim at Standards Standards-
   Track, whereas other applications aim at Informational. Informational RFC.

   Before publication can be requested, however, the draft namespace Namespace
   specification document must undergo an Expert Review process
   [RFC5226] pursuant to the guidelines written here (as well as
   standard RFC publication guidelines).  The template defined in
   Appendix A SHOULD be included as part of an RFC-to-be defining some
   other aspect(s) of the namespace, or Namespace, but it may MAY be put forward as a
   Namespace definition document in its own right.  The proposed
   template (including a pointer to a readily available copy of the
   registration document) should be sent to the mailing
   list for review.  This list is monitored by the designated expert(s).
   The applicant has to allow for a two-week [[ four-week ? ]] discussion period for
   clarifying the expression of the registration information, and SHOULD
   improve the namespace Namespace document and/or registration template based on
   the comments received, under the guidance of the designated
   expert(s), before the IESG reviews the document.

   Working groups generally SHOULD seek early expert review for a
   Namespace definition document, before they hand it over to the IESG,
   and individual applicants are also advised to seek expert comments
   early enough.  The aforementioned list can be contacted for informal
   advice at any stage.

4.4.  Registration Documents

   The following subsections describe essential, MANDATORY parts of URN
   Namespace registration documents, which will be focal in the expert
   Review process and IETF Review.

4.4.1.  Namespace Considerations in Registration Documents

   The namespace Namespace definition document MUST include a "Namespace
   Considerations" section that outlines the perceived need for a new
   namespace (i.e., where existing namespaces fall short of the
   proposer's requirements).  Part of the expected elaborations need to
   be the arguments why other identifier systems, in particular a
   specific/new URI Scheme would not be suitable for the intended

   Considerations MUST include, directly or with the help of referenced
   stable (and preferably readily available) documents:

      -  URN assignment procedures;

      -  URN resolution/delegation;

      -  type of resources to be identified;

      -  type of services to be supported.

   NOTE: It is expected that more than one namespace Namespace may serve the same
   "functional" purpose; the intent of the "Namespace Considerations"
   section is to provide a record of the proposer's "due diligence" in
   exploring existing possibilities, for the IESG's consideration.

   [[ Editorial Note: See the endnote of the next section!
   In particular, the above list (from RFC 3406) seems to be rather
   orthogonal to the primary purpose of such section (as indicated in
   the first paragraph), namely to provide evidence for the perceived
   need for the new namespace. Namespace. ]]

4.4.2.  Community Considerations in Registration Documents

   The namespace Namespace definition document MUST also include a "Community
   Considerations" section that indicates the dimensions upon which the
   proposer expects its community to be able to benefit by publication
   of this namespace, Namespace, as well as how a general Internet user will be
   able to use the space if they care to do so.

   Potential considerations include:

      -  open assignment and use of identifiers within the namespace; Namespace;

      -  open operation of resolution servers for the namespace Namespace

      -  creation of software that can meaningfully resolve and access
         services for the namespace Namespace (client).

   [[ Editorial Note:
   It is acknowledged that, in many cases, the Namespace Considerations
   and Community Considerations are closely intertwined.  Further, the
   bulleted lists above (from RFC 3406) seems to be more related to the
   items in the registration template entitled "Identifier uniqueness
   considerations", "Identifier persistence considerations", "Process of
   identifier assignment", and "Process for identifier resolution" than
   to the primary objectives presented in the first paragraph above
   (also from RFC 3406).
   In fact, namespace Namespace registration documents seen so far duplicate in
   the registration template material from the "Community
   Considerations" that addresses the above bullets.
   Therefore: Should this specification now allow a combined section
   "Namespace and Community Considerations" that focuses on the
   (non-)utility of possible alternate namespace re-use and the
   *benefits* of an independent new namespace? Namespace?

4.4.3.  Security Considerations in Registration Documents

   According to the general procurements for RFCs, URN Namespace
   definition documents must include a "Security Considerations" section
   (cf. BCP 72 [RFC3552]).  That section has to identify the security
   considerations specific to the subject URN Namespace.  If the subject
   URN Namespace is based on an underlying namespace, the registration
   can include substantive security considerations described in
   specifications related to that particular namespace by reference to
   these documents.  For general security considerations regarding URN
   usage (and more generally, URI usage), for the sake of clarity and
   brevity, it should refer to the Security Considerations in STD 63
   [RFC3986] and in the URN Syntax document

4.4.4.  IANA Considerations in Registration Documents

   According to the general procurements for RFCs, URN Namespace
   definitions documents must include an "IANA Considerations" section
   (cf. BCP 26 [RFC5226]).  That section has to indicate that the
   document includes a URN Namespace registration that is to be entered
   into the IANA registry of Formal URN Namespaces.

   Registration documents for formal URN Namespaces will provide a
   particular, unique, desired NID string, and this will be assigned by
   the Standards/Protocol Action of the IESG that approves the
   publication of the registration document as an RFC.  RFC 2141bis
   [I-D.ietf-urnbis-rfc2141bis-urn] specifies that NID strings are ASCII
   strings that are interpreted in a case-insensitive manner, but the
   NID string SHALL be registered in the capitalization form preferred
   by the registrant.  The proposed NID string MUST conform with the
   <nid> syntax rule in Section 2.1 of RFC 2141bis
   [I-D.ietf-urnbis-rfc2141bis-urn] and it MUST adhere to the following
   additional constraints:

      -  not be an already-registered NID;

      -  not start with "X-" (see Section 4.1 above);

      -  not start with "urn-" (see Section 4.2 above);

      -  not start with "xy-", where xy is any combination of 2 ASCII
         letters (see NOTE below);

      -  not be equalt to or start with "example" (see NOTE below);

      -  be more than 2 characters long.

   NOTE: All two-letter combinations as well as two-letter combinations
   followed by "-" and any sequence of valid NID characters are reserved
   for potential future use as countrycode-based NIDs for eventual
   national registrations of URN Namespaces.  The definition and scoping
   of rules for allocation of responsibility for such namespaces Namespaces is
   beyond the scope of this document.
   Further, to avoid confusion, "urn" is not allowed as an NID string;
   To allow neutral example URNs in code and documentation, NID strings
   starting with "example" are set aside for use in documentation; IANA
   has permanently reserved this these string to prohibit assignment.

   Registrations may be revised by updating

   Applicants and the RFC through standard
   IETF RFC update processes.  In any case, a IANA experts have to ensure that the sought NID
   strings are suitable and proper for the designated purpose and not
   misleading, according to common sense and applicable legal rules.
   The IETF Review process gives interested parties the opportunity to
   rise concerns if they want to challenge proposed strings; the final
   approval decision still remains with the IESG.

   Registrations may be revised by updating the RFC through standard
   IETF RFC update processes.  In any case, a revised document, in the
   form of a new Internet-Draft, must be published, and the proposed
   updated template must be circulated on the urn-nid discussion list,
   allowing for a two-week [[ four-week ? ]] review period before pursuing RFC
   publication of the new document.

5.  Security Considerations

   This document largely focuses on providing mechanisms for the
   declaration of public information.  Nominally, these declarations
   should be of relatively low security profile, however profile; however, there is
   always the danger of "spoofing" and providing mis-information.
   Information in these declarations should be taken as advisory.

6.  IANA Considerations

   This document outlines the processes for registering URN Namespaces,
   and has implications for the IANA in terms of registries to be
   maintained, as previously defined in RFC 3406 [RFC3406].  This
   document replaces RFC 3406; it contains a revised description for the
   management of the "Uniform Resource Names (URN) Namespaces" IANA
   Registry that uses the policy designation terms from BCP 26, RFC 5226
   [RFC5226], but does not introduce significant changes to the
   applicable procedures.

   Until recently, that registry has been available in HTML, XML, and
   plain text from the generic web page at
   <> [IANA-URN].

   [[ NOTE: It would be preferable to restore the generic, most
   universally supported (HTML) form of the registry be identified by an
   implementation-neutral URL, as previously supported by IANA:
   <>.  Yet, currently
   this URI and similar forms all resolve to an XML version.
   The content there should link to alternate forms (.xml, .txt), and
   those alternate versions should indicate the *other* versions; i.e.,
   where the .txt version (currently only available at ftp.IANA.ORG)
   also says, "This registry is also available in XML and plain text
   formats.", it should better say: "This registry is also available in
   HTML and XML formats."  Similarly, the XML form should point to the
   HTML and plain text forms. ]]

   All references there to the predecessor, [RFC3406], should be
   replaced by references to this document.
   We would appreciate a reorganization of the Registry web page to make
   the registration templates for Informal URN Namespaces directly
   linked from the main page; this would make the page /assignments/
   urn-informal.htm page dispensable (for persistency's sake, the web
   server should redirect requests to the /assignments/urn-namespaces

   Section 4 of this document outlines the general procedures.
   Section 4.4.4 above describes the syntax rules for NIDs to which the
   registry needs to obey.

   As pointed out in Section 4.4.4 above and in RFC 2141bis
   [I-D.ietf-urnbis-rfc2141bis-urn], the string "urn" is permanently
   reserved and MUST NOT be assigned as an NID.  All strings starting
   with "example" are permanently reserved for use in code and
   documentation, and hence MUST NOT be assigned as an NID.

   In all cases of new namespace Namespace registration proposals, the IANA should
   provisionally assign the appropriate NID (informal or formal), as
   described throughout the body of this memo, once an IESG-designated
   expert has confirmed that the requisite registration process steps
   have been completed.  These registrations become permanent and can be
   made publicly available once the registration document has been
   approved by the IESG for publications as a Standards Track Standards-Track or
   Informational RFC.

7.  Acknowledgements

   This document is heavily based on RFC 3406, the authors of which are
   cordially acknowledged.

   This document also been inspired by other recent documents that have
   updated important IANA registries, and the countless authors and
   contributors to these efforts are acknowledged anonymously.

   Several individuals in the URNbis working group have participated in
   the detailed discussion of this memo.  Particular thanks for detailed
   review comments and text suggestions go to Juha Hakala Hakala, Peter Saint-
   Andre, and Mykyta Yevstifeyev.

8.  References

8.1.  Normative References

              Hoenes, A., "Uniform Resource Name (URN) Syntax",
              draft-ietf-urnbis-rfc2141bis-urn-02 (work in progress),
              October 2011.
              March 2012.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC3339]  Klyne, G., Ed. and C. Newman, "Date and Time on the
              Internet: Timestamps", RFC 3339, July 2002.

   [RFC3986]  Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
              Resource Identifier (URI): Generic Syntax", STD 66,
              RFC 3986, January 2005.

   [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs", BCP 26, RFC 5226,
              May 2008.

8.2.  Informative References

   [IANA]     IANA, "The Internet Assigned Numbers Authority",

   [IANA-URI] IANA, "URI Schemes Registry",

   [IANA-URN] IANA, "Uniform Resource Names (URN) Namespace Registry",

   [RFC2276]  Sollins, K., "Architectural Principles of Uniform Resource
              Name Resolution", RFC 2276, January 1998.

   [RFC2611]  Daigle, L., van Gulik, D., Iannella, R., and P. Faltstrom,
              "URN Namespace Definition Mechanisms", BCP 33, RFC 2611,
              June 1999.

   [RFC3305]  Mealling, M. and R. Denenberg, "Report from the Joint W3C/
              IETF URI Planning Interest Group: Uniform Resource
              Identifiers (URIs), URLs, and Uniform Resource Names
              (URNs): Clarifications and Recommendations", RFC 3305,
              August 2002.

   [RFC3401]  Mealling, M., "Dynamic Delegation Discovery System (DDDS)
              Part One: The Comprehensive DDDS", RFC 3401, October 2002.

   [RFC3405]  Mealling, M., "Dynamic Delegation Discovery System (DDDS)
              Part Five: URI.ARPA Assignment Procedures", BCP 65,
              RFC 3405, October 2002.

   [RFC3406]  Daigle, L., van Gulik, D., Iannella, R., and P. Faltstrom,
              "Uniform Resource Names (URN) Namespace Definition
              Mechanisms", BCP 66, RFC 3406, October 2002.

   [RFC3552]  Rescorla, E. and B. Korver, "Guidelines for Writing RFC
              Text on Security Considerations", BCP 72, RFC 3552,
              July 2003.

   [RFC4020]  Kompella, K. and A. Zinin, "Early IANA Allocation of
              Standards Track Code Points", BCP 100, RFC 4020,
              February 2005.

   [RFC4395]  Hansen, T., Hardie, T., and L. Masinter, "Guidelines and
              Registration Procedures for New URI Schemes", BCP 35,
              RFC 4395, February 2006.

   [RFC5234]  Crocker, D. and P. Overell, "Augmented BNF for Syntax
              Specifications: ABNF", STD 68, RFC 5234, January 2008.

Appendix A.  URN Namespace Definition Template

   Definition of a URN Namespace is accomplished by completing the
   following information template.
   Apart from providing a mechanism for disclosing the structure of the
   URN Namespace, this information is designed to be useful for

   -  entities seeking to have a URN assigned in a namespace Namespace (if
      applicable) and

   -  entities seeking to provide URN resolvers for a namespace Namespace (if

   This is particularly important for communities evaluating the
   possibility of using a portion of an existing URN Namespace rather
   than creating their own.

   Applications for Formal URN Namespaces must also document "Namespace
   Considerations", "Community Considerations", "Security
   Considerations", and "IANA Considerations", as described in
   Section 4.4.

   Information in the template is as follows (text in curly braces is
   tutorial and should be removed from filled-in templates):

   Namespace ID:

      { If request is for an Informal NID, indicate so; the number will
      be assigned by IANA.  In the case of a Formal NID registration,
      regularly a particular NID string will be requested. }

   Registration Information:

      { This is information to identify the particular version of
      registration information: }
      -  version number:
         { starting with 1, incrementing by 1 with each new version }
      -  date:
         { date submitted to the IANA or date of approval of
         registration document, using the format outlined in "Date and
         Time on the Internet: Timestamps", [RFC3339]: YYYY-MM-DD }

   Declared registrant of the namespace: Namespace:

      -  Registering organization:
           Name: { ... }
           Address: { ... }
      -  Designated contact person:
           Name: { ... }
         { Address: ...
           (at least one of: Email, Phone, Postal address) }

   Declaration of syntactic structure of NSS part:

      [[ Editorial

      { Note: In the past, there has been iterated trouble in tentative
      registration documents with confusion between entire URN syntax
      and NSS syntax (only).  Since the "urn:" prefix is fixed and the
      NID is fully determined by the "Namespace ID" clause above, in
      order to avoid error prone duplication, this version of the
      template tentatively restricts this clause to the NSS
      (namespace specific string) (Namespace Specific
      String) part of the new URNs. ]] }

      This section should outline any structural features of identifiers
      in this namespace. Namespace.  At the very least, this description may be
      used to introduce terminology used in other sections.  This
      structure may also be used for determining realistic caching/
      shortcuts approaches; suitable caveats should be provided.  If
      there are any specific character encoding rules (e.g., which
      character should always be used for single-quotes), these should
      be listed here.

      Answers might include, but are not limited to:
      -  the structure is opaque (no exposition);
      -  a regular expression for parsing the identifier into
         components, including naming authorities;
      -  formal syntax of the NSS, preferably in ABNF (STD 68

   Relevant ancillary documentation:

      This section should list any RFCs, standards, or other published
      documentation that defines or explains all or part of the
      namespace structure.

      Answers might include, but are not limited to:
      -  RFCs that outline the syntax of the namespace;
      -  other documents of the defining community (e.g., ISO) that
         outline the syntax of the identifiers in the namespace;
      -  explanatory material that introduces the namespace.

   Conformance with URN Syntax:

      [[ Editorial Note: This clause moved into vicinity of "syntax". ]]

      This section should outline any special considerations required
      for conforming with the URN syntax.  This is particularly
      applicable in the case of legacy naming systems that are used in
      the context of URNs.

      For example, if a namespace is used in contexts other than URNs,
      it may make use of characters that are reserved in the URN syntax.

      This section should flag any such characters, and outline
      necessary mappings to conform to URN syntax.  Normally, this will
      be handled by percent-encoding the symbol.

   Rules for Lexical Equivalence of NSS part:

      [[ Editorial Note: This clause moved into vicinity of "syntax". ]]

      [[ Editorial

      { Note: In the past, there has been iterated trouble in tentative
      registration documents with regard to what rules can be imposed
      for lexical equivalence.  Since the "urn:" prefix and the NID part
      both are invariably case-insensitive per RFC 3986 and RFC
      2141[bis], 2141bis,
      in order to avoid repeated confusion, this version of the template
      tentatively restricts this clause to only the NSS part of the new URN Namespace definition documents. ]]
      newly specified URNs. }
      If there are particular algorithms for determining equivalence
      between two identifiers in the underlying namespace (and hence, in
      the URN string itself), rules can be provided here.

      Some examples include:
      -  equivalence between hyphenated and non-hyphenated groupings in
         the identifier string;
      -  equivalence between single-quotes and double-quotes;
      -  namespace-defined equivalences between specific characters,
         such as "character X with or without diacritic marks".

      Note that these are not normative statements for any kind of best
      practice for handling equivalences between characters; they are
      statements limited to reflecting the namespace's own rules.

      However, namespaces that seek to provide higher-level lexical
      equivalence rules should preferably make use of established and
      standardized normalization procedures (like the methods leading to
      the various Unicode Normalization Forms, which would have to be
      applied before UTF-8 encoding) and not invent their own "magic";
      in practice, the utility of such things is likely to be limited
      since test of lexical equivalence is a typical client-side pre-
      screening operation performed by applications that try to remain
      as general as possible and typically will not have built-in, NID-
      specific knowledge -- ultimately, functional (or semantical)
      equivalence of URNs can only be decided in the NID-specific
      assignment/resolution systems, and their internal rules can be
      handled much more flexibly than more complicated, nailed-down
      lexical equivalence rules that are unlikely to be implemented at

   Identifier uniqueness considerations:

      This section should address the requirement that URN identifiers
      be assigned uniquely -- they are assigned to at most one resource,
      and are not reassigned.

      (Note that the definition of "resource" is fairly broad; for
      example, information on "Today's Weather" might be considered a
      single resource, although the content is dynamic.)
      Possible answers include, but are not limited to:
      -  exposition of the structure of the identifiers, and
         partitioning of the space of identifiers amongst assignment
         authorities that are individually responsible for respecting
         uniqueness rules;
      -  identifiers are assigned sequentially;
      -  information is withheld; that is, the namespace is opaque.

   Identifier persistence considerations:

      Although non-reassignment of URN identifiers ensures that a URN
      will persist in identifying a particular resource even after the
      "lifetime of the resource", some consideration should be given to
      the persistence of the usability of the URN.  This is particularly
      important in the case of URN Namespaces providing global

      Possible answers include, but are not limited to:
      -  quality of service considerations.

   Process of identifier assignment:

      This section should detail the mechanisms and/or authorities for
      assigning URNs to resources.  It should make clear whether
      assignment is completely open, or if limited, how to become an
      assigner of identifiers, and/or get one assigned by existing
      assignment authorities.

      Answers could include, but are not limited to:
      -  assignment is completely open, following a particular
      -  assignment is delegated to authorities recognized by a
         particular organization (e.g., the Digital Object Identifier
         Foundation controls the DOI assignment space and its
      -  assignment is completely closed (e.g., for a private

   Process for identifier resolution:

      If a namespace Namespace is intended to be accessible for global resolution,
      it must be registered in an RDS (Resolution Discovery System, see
      RFC 2276 [RFC2276]) such as the DDDS (see RFC 3401 [RFC3401]).
      Resolution then proceeds according to standard URI resolution
      processes, and the mechanisms of the RDS.  What this section
      should outline is the requirements for becoming a recognized
      resolver of URNs in this namespace Namespace (and being so listed in the RDS

      Answers may include, but are not limited to:
      -  the namespace Namespace is not listed with an RDS, this is not relevant;
      -  resolution mirroring is completely open, with a mechanism for
         updating an appropriate RDS;
      -  resolution is controlled by entities to which assignment has
         been delegated.

   Validation mechanism:

      Apart from attempting resolution of a URN, a URN Namespace may
      provide mechanisms for "validating" a URN -- i.e., determining
      whether a given string is currently a validly-assigned URN.  There
      are 2 issues here: 1) users should not "guess" URNs in a
      Namespace; 2) when the URN Namespace is based on an existing
      identifier system, it may not be the case that all the existing
      identifiers are assigned on Day 0.  The reasonable expectation is
      that the resource associated with each resulting URN is somehow
      related to the thing identified by the original identifier system,
      but those resources may not exist for each original identifier.
      For example, even if a telephone number-based URN Namespace was
      created, it is not clear that all telephone numbers would
      immediately become "valid" URNs, that could be resolved using
      whatever mechanisms are described as part of the namespace Namespace

      Validation mechanisms might be:
      -  a syntax grammar;
      -  an on-line service;
      -  an off-line service.


      This section should outline the scope of the use of the
      identifiers in this namespace. namespace, i.e. the precise kind of resources
      to which the URNs are assigned.  Apart from considerations of
      private vs. public namespaces, this section is critical in
      evaluating the applicability of a requested NID.  For example, a
      namespace claiming to deal with "social security numbers" should
      have a global scope and address all social security number
      structures (unlikely).  On the other hand, at a national level, it
      is reasonable to propose a URN Namespace for "this nation's social
      security numbers".

Appendix B.  Illustration

B.1.  Example Template

   [[ Editorial Note: Do we really need this any more?
   Such an almost-concrete example likely contradicts current IESG
   policy on usage of examples  Registration steps in RFCs. ]] practice

   The following example is provided key steps for registration of Informal or Formal Namespaces
   typically play out as follows:

   A) Informal NID:

      1.  Complete the purposes registration template.  This may be done as part
          of illustrating an Internet-Draft.

      2.  Communicate the URN NID registration template described in Appendix A.  Although it is based
   on to for
          technical review -- as an email with a hypothetical "generic Internet namespace" that has been
   discussed informally within pointer to the URN WG, there are still technical
          submitted I-D or inline text containing the template.

      3.  Update the registration template (and/or document) as
          necessary from comments, and
   infrastructural issues that would have to be resolved before such a
   namespace could be properly and completely described.

   Namespace ID:

      To be assigned

   Registration Information:

      -  version number:  1
      -  date:  <when submitted>

   Declared registrant of the namespace:

      -  Registering organization:
         Name:      Thinking Cat Example Enterprises
         Postal:    1 ThinkingCat Way
                    Trupville, NewCountry

      -  Designated contact person:
         Name:      L. Daigle
         Email:     leslie@thinkingcat.example

   Declaration of syntactic structure of NSS part:

      The namespace specific string structure is as follows:

         <FQDN>:<assigned string>

      where FQDN is a fully-qualified domain name, and the assigned
      string is conformant to URN syntax requirements.

   Relevant ancillary documentation:

      Definition of domain names, found in:

      RFC 1034, November 1987.

      STD 13, RFC 1035, November 1987.

   Conformance with URN Syntax:

      No special considerations.

   Rules for Lexical Equivalence of NSS part:

      FQDNs are case-insensitive.  Thus, the leading portion of the URN
      up to the colon after the FQDN is case-insensitive for matches.
      The remainder of the identifier must be considered case-sensitive.

   Identifier uniqueness considerations:

      Uniqueness is guaranteed as long as the assigned string is never
      reassigned for a given FQDN, and that the FQDN is never

      N.B.: operationally, there is nothing that prevents a domain name
      from being reassigned; indeed, it is not an uncommon occurrence.
      This is one of the reasons that this example makes a poor URN
      namespace in practice, and is therefore not seriously being
      proposed as it stands.

   Identifier persistence considerations:

      Persistence of identifiers is dependent upon suitable delegation
      of resolution at the level of "FQDN"s, and persistence of FQDN

      Same note as above.

   Process of identifier assignment:

      Assignment of these URNs is delegated to individual domain name
      holders (for FQDNs).  The holder of the FQDN registration is
      required to maintain an entry (or delegate it) in the DDDS.
      Within each of these delegated name partitions, the string may be
      assigned per local requirements.

      E.g., urn:urn-<assigned number>:thinkingcat.example:001203

   Process for identifier resolution:

      Domain name holders are responsible for operating or delegating
      resolution servers for the FQDN in which they have assigned URNs.

   Validation mechanism:

      None specified.



B.2.  Registration steps in practice

   The key steps for registration of informal or formal namespaces
   typically play out as follows:

   A) Informal NID:

      1.  Complete the registration template.  This may be done as part
          of an Internet-Draft.

      2.  Communicate the registration template to for
          technical review -- as an email with a pointer to the
          submitted I-D or inline text containing the template.

      3.  Update the registration template (and/or document) as
          necessary from comments, and repeat steps 2 and 3 as

      4.  Once comments repeat steps 2 and 3 as

      4.  Once comments have been addressed (and the review period has
          expired), send a request to IANA with the revised registration

   B) Formal NID:

      1.  Write an Internet-Draft describing the namespace and include
          the registration template, duly completed.  Be sure to include
          "Namespace Considerations", Considerations" and "Community Considerations", Considerations"
          sections (or a combined section for these), "Security Considerations",
          Considerations" and "IANA Considerations" sections, as
          described in Section 4.4.

      2.  Submit the Internet-Draft, and send a pointer to the I-D
          (perhaps using a copy of the I-D announcement) to
 in order to solicit technical review.

      3.  Update the Internet-Draft as necessary from comments, and
          repeat steps 2 and 3 as needed.

      4.  If the Internet-Draft is the product of a working group in the
          IETF, follow the usual WG process to forward the document to
          the IESG for publication as an RFC.  Otherwise, find a
          sponsoring Area Director willing to guide the draft through
          the IESG.  The IESG (or the IETF at large in case an IETF-wide
          last call is deemed necessary) may request further changes
          (submitted as I-D revisions) and/or direct discussion to
          designated working groups, area experts, etc.

      5.  The IESG evaluation process includes a review by IANA, and if
          the IESG approves the document for publication as an RFC, IANA
          processing of the document will follow the regular work-flow
          between the RFC Editor and IANA.  This way, the NID
          registration will be made public by IANA when the RFC is

Appendix C.  Changes from RFC 3406

C.1.  Essential Changes since RFC 3406

   [ RFC Editor: please remove the Appendix C.1 headline and all
   subsequent subsections of Appendix C starting with Appendix C.2. ]

   T.B.D. (after consolidation of this memo)

C.2.  Changes from RFC 3406 to URNbis WG Draft -00

   o  Abstract: rewritten entirely;

   o  Section 1 (Introduction): added historical RFC information;

   o  Section 1.1 (Requirements Language): added;

   o  Section 3.1: added Note that challenges the utility of
      Experimental namespaces Namespaces and raises question of whether formal
      "provisional" registrations would be useful;

   o  Section 4: text expanded and updated; background material added;
      added Note to challenge IANA website practices;

   o  Section 4.2 ff: changed "home" of URN-NID registration discussion
      list (it already had been moved to the IETF Secretariat servers);

   o  Section 4.2: added Note to challenge the 2-week review period; in
      current practice, that is almost always exceeded, and some regard
      it as too short;

   o  Section 4.3: largely clarified procedures as they happen in
      practice; adapted language for conformance with RFC 5226; use new
      home of URN-NID (as mentioned above); the registration template
      (Appendix A) now "SHOULD" be used;

   o  Section 4.3: split off new Section 4.4 on Registration Documents,
      because registrants essentially are encouraged to follow these
      guidelines for Informal namespaces Namespaces as well, as far as practical;
      replaced "RFC" by "Registration Document"; Section 4.4 is
      subdivided for all mandatory sections;

   o  Section 4.4.1: made requirements a "MUST";

   o  Sections 4.4.1 and 4.4.2: added common Note that challenges the
      need to split Namespace and Community Considerations, based on
      observed problems in practice to separate the topics, and pointing
      to overlap with clauses in the registration template due to
      bullets listed that are not so clearly related to the headlines
      under which they appear; suggestion is to avoid duplication, place
      factual stuff into the template and focus on rationale in these
      Considerations, perhaps in a common section;

   o  Section 4.4.3: added discussion of Security Considerations
      section; advice is to focus on namespace-specific considerations
      and refer to the SecCons in the "generic" RFCs for the general

   o  Section 4.4.4: amended discussion of IANA Considerations section;
      this tries to reflect standing practice and codifies that Formal
      NIDs are generally proposed by the registrant; added Note that
      "urn" is permanently reserved and MUST NOT be assigned as a NID,
      to avoid confusion (as also specified in RFC 2141bis draft); wrt
      registration maintenance: got rid of wrong reference in RFC 3406
      (to RFC 2606);

   o  Section 6 (IANA Considerations): updated and rephrased description
      of the role of this document, including a sketch of the history;
      added teat that tries to precisely describe what is expected from
      IANA on approval of this draft; added text on procedures and
      suggest a provisional assignment practice upon "thumbs-up" of the
      IANA Expert to protect prospective registrants from collateral
      damage on NID precedence in case the document suffers from delays
      unrelated to the registration template before it eventually gets

   o  Section 7 (Acknowledgements): added;

   o  References: Updated and amended references; added pointers to
      chartered URNbis work items; removed entirely outdated example
      material related to legacy documents;

   o  Appendix A and B.1: added words on Security Considerations

   o  Appendix A (Registration Template): clarified role of text
      snippets in the Template: hint and commentary now all enclosed in
      curly braces, with not that these parts shall be removed when
      filling in the tempalte; indicate that Formal NIDs are normally
      proposed by registrant; changed date/time ref. from ISO 8601 to
      RFC 3339; use inherited term "percent-encoding";

   o  Appendix A -- structure: moved formal clauses on Conformance with
      URN Syntax and Rules for Lexical Equivalence to vicinity of
      namespace specific syntax clause, to which these are closely

   o  Appendix A -- changes of clauses: the Declaration of syntactic
      structure and Rules for Lexical Equivalence clauses now
      tentatively have been restricted to the NSS part only; this change
      is described in NOTEs and motivated by the observation of repeated
      confusion in past and present registration documents, which
      hopefully can be avoided (and the job of the Expert and reviewers
      made easier) by leaving discussion of the invariate parts that
      cannot be re-specified there at the single place where they belong
      to: the NID is fully specified in the initial clause, rules for
      the NID and the URI scheme name "urn" are inherited from RFC
      2141[bis] and RFC 3986, respectively, and hence the new clause
      descriptions avoid conflict by taking these components out of
      scope of these clauses;

   o  Appendix B.1 (Example Template): facelifted a bit; concerns with
      IESG policy on examples in RFCs raised in a NOTE;

   o  Appendix B.2 (Registration steps in practice): updated and
      clarified description of procedure, in alignment to current

   o  Appendix C: removed "Changes from RFC 2611"; added this change

   o  General: numerous editorial changes and enhancements, following
      contemporary RFC style.

C.3.  Changes from URNbis WG I-D -00 to -01

   Usage of terminology strenghtened.

   Clarified role and usage of Experimental Namespaces.

   Clarified NID strings for Formal Namespaces.

   Added hint that recommends Std. Track RFCs for NID applications based
   on established standard namespaces, and Informational for others.

   Changed standard review period from 2 to 4 weeks (pending

   Resolved with IANA: simple, traditional and generic URL used by IANA
   for the URN Namespace registry.  (Needed to be re-opened in -02!)

   Numerous editorial enhancements and fixes.

C.4.  Changes from URNbis WG I-D -01 to -02

   General text edits based on evaluation of meeting and on-list

   Updated and tightened the organizatorial requirements for Formal
   Namespace requests.

   Restored additional IANA Considerations -- due to observed defects.

   Reserved NID strings "example.*" for documentation (as suggested by
   Larry Masinter, Peter Saint-Andre, and Julian Reschke).

   Added text on possible "higher level" methods to establish lexical
   equivalence of URNs, with the caveats that such things are rather
   unlikely to get traction in general-purpose client software.

   Removed historical Appendix B.1 (Example Template).

   Various editorial enhancements and fixes.

   Updated and expanded "Issues" Appendix (below) in preparation of
   usage of the IETF Issue Tracker.

Appendix D.  Open  Issues in this Draft

   [ Appendix to be replaced by use of IETF Tools issue tracker. ]

   For more details on the issues below, please also see the Editorial
   Notes interspersed in the body of this draft.

   Discuss consequences of RFC 2141bis (once consensus is achieved); if
   proposal for fragment part is adopted, details need to be described
   per namespace Namespace that wants to adopt these possibilities, and maybe the
   registration template needs a new clause where this will be specified
   -- or the information has to be assigned assigned to existing clauses.

   Do registration documents need more guidance and be caused to existing clauses.

   More be more
   precise in their elaboration on Services. the applicability of Services?  Since
   RFC 2483 is considered outdated, but RFC 2483bis not yet alife (nor a
   URNbis work item, item), we might need a registry for URN Services
   (initially populated from RFC 2483) that can be referred to in namespace
   Namespace registration documents, thus avoiding normative
   dependencies on a future RFC 2483bis.

   Do we actually need Experimental Namespaces?
   [Regarded as CLOSED affirmatively at IETF 80.]
   There are concerns regarding usage of "X-" NIDs, which is reported to
   having proven impractical in practice.  This draft version contains
   tentative text to address these concerns; "X-" is now demoted to
   "SHOULD" level.

   The syntax of the NID strings for the various NID types is given in
   an informal manner (as has been done in RFC 3406); is it worth the
   effort to introduce ABNF for this purpose?
   [The request for ABNF has been voiced only once; the document Editor
   regards this issue as CLOSED.]

   Increase review/timeout periods for urn-nid list and IANA experts
   from 2 to 4 (or more) weeks?  This draft version tentatively
   specifies 4 weeks.
   Juha Hakala has argued that the assessment of the responsible
   organizations needed to assure their ability to properly operate the
   Namespace could never be performed within the present 2 weeks time
   span; 8 weeks might be an even better choice for the future upper
   limit for the review period.  It has been pointed out that even 8
   weeks are miniscule with regard to the expected lifetime of the to-
   be-registered Namespace and hence should not matter.  In practice,
   the subsequent IESG evaluation of URN Namespace registration
   documents has typically needed much longer time.

   Clarification of the desired content of the "Namespace
   Considerations" and "Community Considerations" sections in
   registration documents.  Shall we admit a combined section for both
   topics? (so far supported by 2 postings) Cf. the NOTEs in Sections
   4.4.1 and 4.4.2 for more details.
   [No feedback on the list since -01, so the draft text seems to have
   silent consensus and the issue is regarded as CLOSED.]
   Shall other strings than beyond "urn" also be 'reserved' in the NID
   registry? (e.g. "uri", "url", "urc", "example", ...)  There have been voices in
   favor of leaving the decision of what is acceptable and reasonable in
   practice to the common sense of prospective registrants and the
   designated IANA experts.  This draft version reserves NID strings
   matching the RE "^example.*" for documentation.

   Appendix A: Once RFC 2483 gets updated and an IANA registry for URN
   resolution services gets established, the "Process for identifier
   resolution" clause in the registration template should call out for
   enumerating the registered services that are applicable for the newly
   defined URN Namespace.
   How far can we go in this respect without an update to RFC 2483 at

   Do we really still need Appendix B.1 ?  (There are lots of real-life
   examples now!)

   Also see the Editorial Notes interspersed in the body of this draft.
   [ Old B.1 removed, old B.2 became Appendix B; ==> CLOSED ]

Author's Address

   Alfred Hoenes
   Gerlinger Str. 12
   Ditzingen  D-71254