IETF URNbis WG A. Hoenes Internet-Draft TR-Sys Obsoletes: 3406 (if approved) March 12, 2012 Intended status: BCP Expires: September 13, 2012 Uniform Resource Name (URN) Namespace Definition Mechanisms draft-ietf-urnbis-rfc3406bis-urn-ns-reg-02 Abstract 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 metadata related to them). To 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 registration documents. This RFC serves as a guideline for authors of URN Namespace definition and registration 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. This document is a companion document to the revised URN Syntax specification, RFC 2141bis; it supersedes and replaces RFC 3406. Discussion Discussion of this memo utilizes the urn@ietf.org mailing list. Hoenes Expires September 13, 2012 [Page 1]
Internet-Draft URN Namespace Definition Mechanisms March 2012 Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on September 13, 2012. Copyright Notice Copyright (c) 2012 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. This document may contain material from IETF Documents or IETF Contributions published or made publicly available before November 10, 2008. The person(s) controlling the copyright in some of this material may not have granted the IETF Trust the right to allow modifications of such material outside the IETF Standards Process. Without obtaining an adequate license from the person(s) controlling the copyright in such materials, this document may not be modified outside the IETF Standards Process, and derivative works of it may not be created outside the IETF Standards Process, except to format it for publication as an RFC or to translate it into languages other than English. Hoenes Expires September 13, 2012 [Page 2]
Internet-Draft URN Namespace Definition Mechanisms March 2012 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 . . . . . . . . . . . . . . 7 3.1. Experimental Namespaces . . . . . . . . . . . . . . . . . 7 3.2. Informal Namespaces . . . . . . . . . . . . . . . . . . . 7 3.3. Formal Namespaces . . . . . . . . . . . . . . . . . . . . 7 4. URN Namespace Registry: Processes for Registration and Update . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 4.1. Experimental Namespaces: No Registration . . . . . . . . . 10 4.2. Informal Namespaces . . . . . . . . . . . . . . . . . . . 10 4.3. Formal Namespaces . . . . . . . . . . . . . . . . . . . . 11 4.4. Registration Documents . . . . . . . . . . . . . . . . . . 12 4.4.1. Namespace Considerations in Registration Documents . . 12 4.4.2. Community Considerations in Registration Documents . . 13 4.4.3. Security Considerations in Registration Documents . . 14 4.4.4. IANA Considerations in Registration Documents . . . . 14 5. Security Considerations . . . . . . . . . . . . . . . . . . . 15 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 16 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 17 8.1. Normative References . . . . . . . . . . . . . . . . . . . 17 8.2. Informative References . . . . . . . . . . . . . . . . . . 17 Appendix A. URN Namespace Definition Template . . . . . . . . . . 18 Appendix B. 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 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 Hoenes Expires September 13, 2012 [Page 3]
Internet-Draft URN Namespace Definition Mechanisms March 2012 1. Introduction Uniform Resource Names (URNs) are resource identifiers adhering to the specific requirements 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 metadata). 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. 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 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 Hoenes Expires September 13, 2012 [Page 4]
Internet-Draft URN Namespace Definition Mechanisms March 2012 Authority (IANA) [IANA] in the URN Namespaces registry maintained at [IANA-URN]. 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", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 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 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 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 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 Hoenes Expires September 13, 2012 [Page 5]
Internet-Draft URN Namespace Definition Mechanisms March 2012 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, for each identifier assigned in the namespace. Once assigned, URNs are 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, 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 is completed for deposit with IANA, and a NID is assigned. The details of the process and possibilities for NID strings are outlined below. Hoenes Expires September 13, 2012 [Page 6]
Internet-Draft URN Namespace Definition Mechanisms March 2012 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 types are given in Section 4. 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. 3.2. Informal Namespaces These are fully fledged URN Namespaces, with all the rights and requirements associated thereto. Informal 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 (described below) differ in the NID assignment. IANA will assign to registered Informal Namespaces a simply structured, alphanumeric, ordinal NID (following a pattern defined in Section 4.2 below), per the process outlined in Section 4. 3.3. Formal Namespaces A 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 Hoenes Expires September 13, 2012 [Page 7]
Internet-Draft URN Namespace Definition Mechanisms March 2012 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 where some aspects are not fully open. For example, a Namespace may make use of a fee-based, privately managed, or proprietary registry for assignment of URNs in the Namespace, but it may still provide benefit to some Internet users if the services associated with it have openly published access protocols. In addition to the basic registration information defined in the registration template (in Appendix A), a Formal Namespace request must be accompanied by documented considerations of the need for a new Namespace and of the community benefit from formally establishing the proposed URN Namespace. Additionally, since the goal of URNs is to provide persistent identification, careful consideration must be given to the longevity and maintainability of the 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 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 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 for a long time, and/or it should be clear how the Namespace can continue to be usable/useful if the organization ceases to be able to foster 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); - 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 Hoenes Expires September 13, 2012 [Page 8]
Internet-Draft URN Namespace Definition Mechanisms March 2012 - the involved organization(s) need to commit to not re-assign existing names; old names MUST continue to be valid, even if the owners or assignees of those names are no longer members or customers of such organization; this does not mean that there needs to be resolution of such names, but that they must not resolve such names to false or stale information and that they must not be reassigned. 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 (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. 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 [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 lifetime. Specific processes are outlined below. The official list of registered URN Namespaces is currently maintained by IANA at [IANA-URN]. The 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. Hoenes Expires September 13, 2012 [Page 9]
Internet-Draft URN Namespace Definition Mechanisms March 2012 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: X-<nid> 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 [I-D.ietf-urnbis-rfc2141bis-urn]. 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 tests. 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: urn-<number> 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. Hoenes Expires September 13, 2012 [Page 10]
Internet-Draft URN Namespace Definition Mechanisms March 2012 Registrants should send a copy of the registration template (as shown in Appendix A), duly completed, to the urn-nid@ietf.org mailing list for review and allow for a four-week discussion period for clarifying the expression of the registration information and suggestions for technical improvements to the Namespace proposal. [[ Editorial NOTE: An even longer time is needed in practice! Should we further increase the upper limit to 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 iana@iana.org . 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 four- week discussion period, and finally resubmitting it to IANA in a message to iana@iana.org . 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 definition and targets publication as an RFC of Informational or 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. 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- Track, whereas other applications aim at Informational RFC. Hoenes Expires September 13, 2012 [Page 11]
Internet-Draft URN Namespace Definition Mechanisms March 2012 Before publication can be requested, however, the draft 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, but it 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 urn-nid@ietf.org mailing list for review. This list is monitored by the designated expert(s). The applicant has to allow for a four-week discussion period for clarifying the expression of the registration information, and SHOULD improve the 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 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 purpose. 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. Hoenes Expires September 13, 2012 [Page 12]
Internet-Draft URN Namespace Definition Mechanisms March 2012 NOTE: It is expected that more than one 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. ]] 4.4.2. Community Considerations in Registration Documents The 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, 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; - open operation of resolution servers for the Namespace (server); - creation of software that can meaningfully resolve and access services for the 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 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? ]] Hoenes Expires September 13, 2012 [Page 13]
Internet-Draft URN Namespace Definition Mechanisms March 2012 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 [I-D.ietf-urnbis-rfc2141bis-urn]. 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. Hoenes Expires September 13, 2012 [Page 14]
Internet-Draft URN Namespace Definition Mechanisms March 2012 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 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 these string to prohibit assignment. Applicants and the 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 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, 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 <http://www.iana.org/assignments/urn-namespaces/> [IANA-URN]. Hoenes Expires September 13, 2012 [Page 15]
Internet-Draft URN Namespace Definition Mechanisms March 2012 [[ 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: <http://www.iana.org/assignments/urn-namespaces>. 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 page. 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 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 or Informational RFC. 7. Acknowledgements This document is heavily based on RFC 3406, the authors of which are cordially acknowledged. Hoenes Expires September 13, 2012 [Page 16]
Internet-Draft URN Namespace Definition Mechanisms March 2012 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, Peter Saint- Andre, and Mykyta Yevstifeyev. 8. References 8.1. Normative References [I-D.ietf-urnbis-rfc2141bis-urn] Hoenes, A., "Uniform Resource Name (URN) Syntax", draft-ietf-urnbis-rfc2141bis-urn-02 (work in progress), 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", <http://www.iana.org/>. [IANA-URN] IANA, "Uniform Resource Names (URN) Namespace Registry", <http://www.iana.org/assignments/urn-namespaces/>. [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. Hoenes Expires September 13, 2012 [Page 17]
Internet-Draft URN Namespace Definition Mechanisms March 2012 [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. [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 (if applicable) and - entities seeking to provide URN resolvers for a Namespace (if applicable). 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): Hoenes Expires September 13, 2012 [Page 18]
Internet-Draft URN Namespace Definition Mechanisms March 2012 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: - Registering organization: Name: { ... } Address: { ... } - Designated contact person: Name: { ... } { Address: ... (at least one of: Email, Phone, Postal address) } Declaration of syntactic structure of NSS part: { 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 restricts this clause to the NSS (Namespace Specific String) part of the new URNs. } { This section should outline any structural features of identifiers in this 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. Hoenes Expires September 13, 2012 [Page 19]
Internet-Draft URN Namespace Definition Mechanisms March 2012 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 [RFC5234]). } 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: { 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: { 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 2141bis, in order to avoid repeated confusion, this version of the template tentatively restricts this clause to only the NSS part of the newly specified URNs. } Hoenes Expires September 13, 2012 [Page 20]
Internet-Draft URN Namespace Definition Mechanisms March 2012 { 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 large. } 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.) Hoenes Expires September 13, 2012 [Page 21]
Internet-Draft URN Namespace Definition Mechanisms March 2012 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 resolution. 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 algorithm; - assignment is delegated to authorities recognized by a particular organization (e.g., the Digital Object Identifier Foundation controls the DOI assignment space and its delegation); - assignment is completely closed (e.g., for a private organization). } Hoenes Expires September 13, 2012 [Page 22]
Internet-Draft URN Namespace Definition Mechanisms March 2012 Process for identifier resolution: { If a 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 (and being so listed in the RDS registry). Answers may include, but are not limited to: - the 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 registration. Validation mechanisms might be: - a syntax grammar; - an on-line service; - an off-line service. } Hoenes Expires September 13, 2012 [Page 23]
Internet-Draft URN Namespace Definition Mechanisms March 2012 Scope: { This section should outline the scope of the use of the identifiers in this 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. 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 urn-nid@ietf.org 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 necessary. 4. Once comments have been addressed (and the review period has expired), send a request to IANA with the revised registration template. B) Formal NID: 1. Write an Internet-Draft describing the namespace and include the registration template, duly completed. Be sure to include "Namespace Considerations" and "Community Considerations" sections (or a combined section for these), "Security 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 urn-nid@ietf.org in order to solicit technical review. Hoenes Expires September 13, 2012 [Page 24]
Internet-Draft URN Namespace Definition Mechanisms March 2012 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 published. 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 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); Hoenes Expires September 13, 2012 [Page 25]
Internet-Draft URN Namespace Definition Mechanisms March 2012 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 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 issues; 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 approved; Hoenes Expires September 13, 2012 [Page 26]
Internet-Draft URN Namespace Definition Mechanisms March 2012 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 section; 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 related; 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 practice; o Appendix C: removed "Changes from RFC 2611"; added this change log; o General: numerous editorial changes and enhancements, following contemporary RFC style. Hoenes Expires September 13, 2012 [Page 27]
Internet-Draft URN Namespace Definition Mechanisms March 2012 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 discussion). 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 comments. 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. 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. Hoenes Expires September 13, 2012 [Page 28]
Internet-Draft URN Namespace Definition Mechanisms March 2012 Discuss consequences of RFC 2141bis (once consensus is achieved); if proposal for fragment part is adopted, details need to be described per 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 to existing clauses. Do registration documents need more guidance and be caused to be more precise in their elaboration on the applicability of Services? Since RFC 2483 is considered outdated, but RFC 2483bis not yet alife (nor a URNbis work item), we might need a registry for URN Services (initially populated from RFC 2483) that can be referred to in 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.] Hoenes Expires September 13, 2012 [Page 29]
Internet-Draft URN Namespace Definition Mechanisms March 2012 Shall other strings beyond "urn" also be 'reserved' in the NID registry? (e.g. "uri", "url", "urc", ...) 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 hands? Do we really still need Appendix B.1 ? (There are lots of real-life examples now!) [ Old B.1 removed, old B.2 became Appendix B; ==> CLOSED ] Author's Address Alfred Hoenes TR-Sys Gerlinger Str. 12 Ditzingen D-71254 Germany EMail: ah@TR-Sys.de Hoenes Expires September 13, 2012 [Page 30]
