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RFC 8141


Uniform Resource Names (URNs)

Part 3 of 3, p. 31 to 40
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7.  IANA Considerations

7.1.  URI Scheme

   This section updates the registration of the "urn" URI scheme in the
   Permanent URI Registry [URI-Registry].

   URI Scheme Name:  urn

   Status:  permanent

   URI Scheme Syntax:  See Section 2 of RFC 8141.

   URI Scheme Semantics:  The "urn" scheme identifies Uniform Resource
      Names, which are persistent, location-independent resource

   Encoding Considerations:  See Section 2 of RFC 8141.

   Applications/Protocols That Use This URI Scheme Name:  Uniform
      Resource Names are used in a wide variety of applications,
      including bibliographic reference systems and as names for
      Extensible Markup Language (XML) namespaces.

   Interoperability Considerations:  See Section 4 of RFC 8141.

   Security Considerations:  See Sections 6.4.4 and 8 of RFC 8141.

   Contact:  URNBIS working group []

   Author/Change Controller:  This scheme is registered under the IETF
      tree.  As such, the IETF maintains change control.

   References:  None.

7.2.  Registration of URN Namespaces

   This document outlines the processes for registering URN namespaces
   and has implications for the IANA in terms of registries to be
   maintained (see especially Section 6).  In all cases, the IANA ought
   to assign the appropriate NID (formal or informal) once the
   procedures outlined in Section 6 have been completed.

7.3.  Discussion List for New and Updated NID Registrations

   As discussed elsewhere in this document, the discussion list
   specified in RFC 3406 ( is discontinued and
   replaced by the discussion list

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8.  Security and Privacy Considerations

   The definition of a URN namespace needs to account for potential
   security and privacy issues related to assignment, use, and
   resolution of names within the URN namespace (e.g., some URN
   resolvers might assign special meaning to certain characters in the
   NSS); see Section 6.4.4 for further discussion.

   In most cases, URN namespaces provide a way to declare public
   information.  Normally, these declarations will have a relatively low
   security profile; however, there is always the danger of "spoofing"
   and providing misinformation.  Information in these declarations
   ought to be taken as advisory.

9.  References

9.1.  Normative References

   [RFC20]    Cerf, V., "ASCII format for network interchange", STD 80,
              RFC 20, DOI 10.17487/RFC0020, October 1969,

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,

   [RFC3986]  Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
              Resource Identifier (URI): Generic Syntax", STD 66,
              RFC 3986, DOI 10.17487/RFC3986, January 2005,

   [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs", BCP 26, RFC 5226,
              DOI 10.17487/RFC5226, May 2008,

   [RFC5234]  Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
              Specifications: ABNF", STD 68, RFC 5234,
              DOI 10.17487/RFC5234, January 2008,

9.2.  Informative References

   [DOI-URI]  Paskin, N., Neylon, E., Hammond, T., and S. Sun, "The
              "doi" URI Scheme for the Digital Object Identifier (DOI)",
              Work in Progress, draft-paskin-doi-uri-04, June 2003.

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   [IANA-URN] Saint-Andre, P. and M. Cotton, "A Uniform Resource Name
              (URN) Namespace for IANA Registries", Work in Progress,
              draft-saintandre-iana-urn-01, February 2013.

              ISO, "Information and documentation - International
              standard name identifier (ISNI)", ISO 27729:2012,
              Technical Committee ISO/TC 46, Information and
              documentation, Subcommittee SC 9, Identification and
              description, March 2012.

              ISO, "Codes for the representation of names of countries
              and their subdivisions -- Part 1: Country codes",
              ISO 3166-1:2013, November 2013.

   [RFC1737]  Sollins, K. and L. Masinter, "Functional Requirements for
              Uniform Resource Names", RFC 1737, DOI 10.17487/RFC1737,
              December 1994, <>.

   [RFC1738]  Berners-Lee, T., Masinter, L., and M. McCahill, "Uniform
              Resource Locators (URL)", RFC 1738, DOI 10.17487/RFC1738,
              December 1994, <>.

   [RFC1808]  Fielding, R., "Relative Uniform Resource Locators",
              RFC 1808, DOI 10.17487/RFC1808, June 1995,

   [RFC2141]  Moats, R., "URN Syntax", RFC 2141, DOI 10.17487/RFC2141,
              May 1997, <>.

   [RFC2276]  Sollins, K., "Architectural Principles of Uniform Resource
              Name Resolution", RFC 2276, DOI 10.17487/RFC2276, January
              1998, <>.

   [RFC2483]  Mealling, M. and R. Daniel, "URI Resolution Services
              Necessary for URN Resolution", RFC 2483,
              DOI 10.17487/RFC2483, January 1999,

   [RFC2648]  Moats, R., "A URN Namespace for IETF Documents", RFC 2648,
              DOI 10.17487/RFC2648, August 1999,

   [RFC3044]  Rozenfeld, S., "Using The ISSN (International Serial
              Standard Number) as URN (Uniform Resource Names) within an
              ISSN-URN Namespace", RFC 3044, DOI 10.17487/RFC3044,
              January 2001, <>.

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   [RFC3187]  Hakala, J. and H. Walravens, "Using International Standard
              Book Numbers as Uniform Resource Names", RFC 3187,
              DOI 10.17487/RFC3187, October 2001,

   [RFC3188]  Hakala, J., "Using National Bibliography Numbers as
              Uniform Resource Names", RFC 3188, DOI 10.17487/RFC3188,
              October 2001, <>.

   [RFC3406]  Daigle, L., van Gulik, D., Iannella, R., and P. Faltstrom,
              "Uniform Resource Names (URN) Namespace Definition
              Mechanisms", BCP 66, RFC 3406, DOI 10.17487/RFC3406,
              October 2002, <>.

   [RFC3552]  Rescorla, E. and B. Korver, "Guidelines for Writing RFC
              Text on Security Considerations", BCP 72, RFC 3552,
              DOI 10.17487/RFC3552, July 2003,

   [RFC4854]  Saint-Andre, P., "A Uniform Resource Name (URN) Namespace
              for Extensions to the Extensible Messaging and Presence
              Protocol (XMPP)", RFC 4854, DOI 10.17487/RFC4854, April
              2007, <>.

   [RFC5122]  Saint-Andre, P., "Internationalized Resource Identifiers
              (IRIs) and Uniform Resource Identifiers (URIs) for the
              Extensible Messaging and Presence Protocol (XMPP)",
              RFC 5122, DOI 10.17487/RFC5122, February 2008,

   [RFC5890]  Klensin, J., "Internationalized Domain Names for
              Applications (IDNA): Definitions and Document Framework",
              RFC 5890, DOI 10.17487/RFC5890, August 2010,

   [RFC6120]  Saint-Andre, P., "Extensible Messaging and Presence
              Protocol (XMPP): Core", RFC 6120, DOI 10.17487/RFC6120,
              March 2011, <>.

   [RFC6288]  Reed, C., "URN Namespace for the Defence Geospatial
              Information Working Group (DGIWG)", RFC 6288,
              DOI 10.17487/RFC6288, August 2011,

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   [RFC6648]  Saint-Andre, P., Crocker, D., and M. Nottingham,
              "Deprecating the "X-" Prefix and Similar Constructs in
              Application Protocols", BCP 178, RFC 6648,
              DOI 10.17487/RFC6648, June 2012,

   [RFC6838]  Freed, N., Klensin, J., and T. Hansen, "Media Type
              Specifications and Registration Procedures", BCP 13,
              RFC 6838, DOI 10.17487/RFC6838, January 2013,

   [RFC6943]  Thaler, D., Ed., "Issues in Identifier Comparison for
              Security Purposes", RFC 6943, DOI 10.17487/RFC6943, May
              2013, <>.

   [RFC6963]  Saint-Andre, P., "A Uniform Resource Name (URN) Namespace
              for Examples", BCP 183, RFC 6963, DOI 10.17487/RFC6963,
              May 2013, <>.

   [RFC6973]  Cooper, A., Tschofenig, H., Aboba, B., Peterson, J.,
              Morris, J., Hansen, M., and R. Smith, "Privacy
              Considerations for Internet Protocols", RFC 6973,
              DOI 10.17487/RFC6973, July 2013,

   [RFC7254]  Montemurro, M., Ed., Allen, A., McDonald, D., and P.
              Gosden, "A Uniform Resource Name Namespace for the Global
              System for Mobile Communications Association (GSMA) and
              the International Mobile station Equipment Identity
              (IMEI)", RFC 7254, DOI 10.17487/RFC7254, May 2014,

   [RFC7282]  Resnick, P., "On Consensus and Humming in the IETF",
              RFC 7282, DOI 10.17487/RFC7282, June 2014,

   [RFC7320]  Nottingham, M., "URI Design and Ownership", BCP 190,
              RFC 7320, DOI 10.17487/RFC7320, July 2014,

   [RFC7462]  Liess, L., Ed., Jesske, R., Johnston, A., Worley, D., and
              P. Kyzivat, "URNs for the Alert-Info Header Field of the
              Session Initiation Protocol (SIP)", RFC 7462,
              DOI 10.17487/RFC7462, March 2015,

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   [RFC7613]  Saint-Andre, P. and A. Melnikov, "Preparation,
              Enforcement, and Comparison of Internationalized Strings
              Representing Usernames and Passwords", RFC 7613,
              DOI 10.17487/RFC7613, August 2015,

   [UAX31]    The Unicode Consortium, "Unicode Standard Annex #31:
              Unicode Identifier and Pattern Syntax", Unicode 9.0.0,
              June 2015, <>.

   [UNICODE]  The Unicode Consortium, "The Unicode Standard",

              IANA, "Uniform Resource Identifier (URI) Schemes",

   [XML-BASE] Marsh, J. and R. Tobin, "XML Base (Second Edition)", W3C
              Recommendation REC-xmlbase-20090128, January 2009,

              Thompson, H., Hollander, D., Layman, A., Bray, T., and R.
              Tobin, "Namespaces in XML 1.0 (Third Edition)", W3C
              Recommendation REC-xml-names-20091208, December 2009,

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Appendix A.  Registration Template

   Namespace Identifier:  Requested of IANA (formal) or assigned by IANA

   Version:  The version of the registration, starting with 1 and
      incrementing by 1 with each new version.

   Date:  The date when the registration is requested of IANA, using the
      format YYYY-MM-DD.

   Registrant:  The person or organization that has registered the NID,
      including the name and address of the registering organization, as
      well as the name and contact information (email, phone number, or
      postal address) of the designated contact person.  If the
      registrant is a recognized standards development organization,
      scientific society, or similar body requesting the fast-track
      registration procedure (see Section 6.3), that information should
      be clearly indicated in this section of the template.

   Purpose:  Described in Section 6.4.1 of this document.

   Syntax:  Described in Section 6.4.2 of this document.  Unless the
      registration explicitly describes the semantics of r-components,
      q-components, and f-components in the context of this URN
      namespace, those semantics are undefined.

   Assignment:  Described in Section 6.4.3 of this document.

   Security and Privacy:  Described in Section 6.4.4 of this document.

   Interoperability:  Described in Section 6.4.5 of this document.

   Resolution:  Described in Section 6.4.6 of this document.

   Documentation:  A pointer to an RFC, a specification published by
      another standards development organization, or another stable
      document that provides further information about this URN

   Additional Information:  Described in Section 6.4.7 of this document.

   Revision Information:  Description of changes from prior version(s).
      (Applicable only when earlier registrations have been revised.)

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Appendix B.  Changes from RFC 2141

   This document makes substantive changes from the syntax and semantics
   of [RFC2141]:

B.1.  Syntax Changes from RFC 2141

   The syntax of URNs as provided in [RFC2141] was defined before the
   updated specification of URIs in [RFC3986].  The definition of URN
   syntax is updated in this document to do the following:

   o  Ensure consistency with the URI syntax.

   o  Facilitate the use of URNs with parameters similar to URI queries
      and fragments.

   o  Permit parameters influencing URN resolution.

   o  Ease the use of URNs with non-URN identifier systems that include
      the "/" character.

   In particular, this specification does the following:

   o  Extends URN syntax to explicitly allow the characters "/", "?",
      and "#", which were reserved for future use by RFC 2141.  This
      change also effectively allows several components of the URI
      syntax although without necessarily tying those components to URI

   o  Defines general syntax for an additional component that can be
      used in interactions with a URN resolution service.

   o  Disallows "-" at the end of the NID.

   o  Allows the "/", "~", and "&" characters in the NSS.

   o  Makes several smaller syntax adjustments.

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B.2.  Other Changes from RFC 2141

   o  Formally registers "urn" as a URI scheme.

   o  Allows what are now called r-components, q-components, and

   In addition, some of the text has been updated to be consistent with
   the definition of URIs [RFC3986] and the processes for registering
   information with the IANA [RFC5226], as well as more modern guidance
   with regard to security [RFC3552], privacy [RFC6973], and identifier
   comparison [RFC6943].

Appendix C.  Changes from RFC 3406

   This document makes the following substantive changes from [RFC3406]:

   1.  Relaxes the registration policy for formal URN namespaces from
       "IETF Review" to "Expert Review" as discussed in Section 6.2.

   2.  Removes the category of experimental URN namespaces, consistent
       with [RFC6648].  Experimental URN namespaces were denoted by
       prefixing the namespace identifier with the string "X-".  Because
       experimental URN namespaces were never registered, removing the
       experimental category has no impact on the existing registries.
       Because experimental URN namespaces are not managed, strings
       conforming to URN syntax within experimental URN namespaces are
       not valid URNs.  Truly experimental usages may, of course, employ
       the "example" namespace [RFC6963].

   3.  Adds some information to, but generally simplifies, the URN
       namespace registration template.

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   Many thanks to Marc Blanchet, Leslie Daigle, Martin Duerst, Juha
   Hakala, Ted Hardie, Alfred Hoenes, Paul Jones, Barry Leiba, Sean
   Leonard, Larry Masinter, Keith Moore, Mark Nottingham, Julian
   Reschke, Lars Svensson, Henry S. Thompson, Dale Worley, and other
   participants in the URNBIS working group for their input.  Alfred
   Hoenes in particular edited an earlier draft version of this document
   and served as co-chair of the URNBIS working group.

   Juha Hakala deserves special recognition for his dedication to
   successfully completing this work, as do Andrew Newton and Melinda
   Shore in their roles as working group co-chairs and Barry Leiba in
   his role as area director and then as co-chair.


   RFC 2141, which provided the basis for the syntax portion of this
   document, was authored by Ryan Moats.

   RFC 3406, which provided the basis for the namespace portion of this
   document, was authored by Leslie Daigle, Dirk-Willem van Gulik,
   Renato Iannella, and Patrik Faltstrom.

   Their work is gratefully acknowledged.

Authors' Addresses

   Peter Saint-Andre
   P.O. Box 787
   Parker, CO  80134
   United States of America

   Phone: +1 720 256 6756
   URI:   <>

   John C. Klensin
   1770 Massachusetts Ave, Ste 322
   Cambridge, MA  02140
   United States of America

   Phone: +1 617 245 1457