The IETF XML Registry

Versions: 00 01 02 03 04 05 rfc3688                                     
Network Working Group                                        M. Mealling
Internet-Draft                                            VeriSign, Inc.
Expires: November 30, 2001                                     June 2001

                         The IETF XML Registry

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   This document is an Internet-Draft and is in full conformance with
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Copyright Notice

   Copyright (C) The Internet Society (2001).  All Rights Reserved.


   This document describes an IANA maintained registry for IETF
   standards which use XML related items such as Namespaces, DTD,
   Schemas, and RDF Schemas.

1. Introduction

   Over the past few years XML [2] has become a widely used method for
   data markup.  There have already been several IETF Working Groups
   that have produced standards that define XML DTDs, XML Namespaces [3]
   and XML Schemas [4].  Each one of these technologies uses URIs [1] to
   identify their respective objects.  For example, a given XML document
   defines its DTD using the DOCTYPE element.  This element, like SGML,

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   has a PUBLIC and a SYSTEM identifier.  It is standard practice within
   W3C standards to forego the use of the PUBLIC identifier in favor of
   'well known' SYSTEM identifiers.  There have been several IETF
   standards that have simply created non-existent URIs in order to
   simply identify but not resolve the SYSTEM identifier for some given
   XML document.

   This document seeks to standardize this practice by creating an IANA
   maintained registry of XML elements so that document authors and
   implementors have a well maintained and authoritative location for
   their XML elements.  As part of this standard, the IANA will both
   house the public representation of the document and either include
   the URI given by the registrant or assign it a Uniform Resource Name
   that can be used as the URI in any URI based identification
   components of XML.

2. Registerable Documents

2.1 The Assigned/Registered URI

   All elements in this registry will require a URI in order to be
   registered.  If the registrant wishes to have a URI assigned  then a
   URN of the form:


   will be assigned where <class> is the type of the document being
   registered (see below).  <id> is a unique id generated by the IANA
   based on any means the IANA deems necessary to maintain uniqueness
   and persistence.  NOTE: in order for a URN of this type to be
   assigned, the item being registered MUST have been through the IETF
   concensus process.  Practically this means it must be documented in
   an RFC.  The RFC XXXX [6] template is found in Section 4.

   The IANA will also maintain a file server available via at least HTTP
   that contains all of the registered elements in some publicly
   accessible file space (in the same way that all of the IANA's
   registered elements are available via  While the directory
   structure of this server is up to the IANA, it is suggested that the
   files be organized by the <class> and the individual files have the
   <id> as their filename.

2.2 Document Types

   The list of types of XML documents that can be registered with the
   IANA are:

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   dtd -- An XML document that contains a DOCTYPE element can identify
      its DTD via both a PUBLIC identifier and a SYSTEM identifier.  The
      URN assigned by the IANA can be used as the value of the SYSTEM

   ns -- XML Namespaces [3]are named by a URI.  They have no real,
      machine-parseable representation other than the specifications
      that define them.  Thus the element registered will be the
      specification (or a pointer to it).  The URN assigned by the IANA
      will be the XML Namespace's name.

   schema -- XML Schemas [4] are also identified by a URI but their
      contents are machine parseable.  The IANA registered document will
      be the XML Schema file.  The URN the IANA assigns can be used as
      the URI for the schema.

   rdfschema -- The Resource Description  Format (RDF) [5] is an XML
      serialization of a connected graph based data model used for
      metadata expression.  RDF makes use of schemas for RDF that
      express grammars about relationships between URIs.  These grammars
      are identified by URIs.  The URN assigned by the IANA can be used
      as the identifying URI.

3. Registration Procedures

   Until such time as the IANA requests or implements an automated
   process for the registration of these elements, any specifications
   wishing to do so must make that request part of the IANA
   considerations section of their respective documents.  That request
   must be in the form of the following template:

      The URI that identifies the XML component.  If the registrant is
      requesting that the IANA assign a URI then this field should be
      specified as "please assign"

   Registrant Contact
      The individual/organization that is the registration contact for
      the component being registered.  Ideally this will be the name and
      pertinent physical and network contact information.

      The exact XML to be stored in the registry.  Unless otherwise
      obvious what the beginning and end of the file are, the document
      should use the text "BEGIN" to mark the beginning of the file and
      "END" to mark the end of the file.  The IANA will insert any text
      between those two strings (minus any page breaks and RFC

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      formatting inserted by the RFC Editor) into the file kept in the

4. IANA Considerations

   This documents seeks to create a rather large registry for which the
   IANA (at the direction of the IESG) will primarily be responsible.
   The amount of effort required to maintain this registry is not
   insignificant and the policies and procedures surrounding any
   approval process are non-trivial.  The registry is on a First Come
   First Served basis but at this time a Specification is Required.  One
   the IETF has some experience with this registry these policies may

   RFC XXXX [6] specifies that any new registry that requires a name to
   be assigned below the 'urn:ietf:params' namespace must specify the
   structure of that space in template form.  The IANA is directed to
   create and maintain this new sub-namespace:

   Registry-name: xml

   Specification: This document contains the registry specification.
      The namespace is organized with one sub-namespace which is the

   Repository: To be assigned according to the guidelines found above.

   Index value: The class name


   [1]  Berners-Lee, T., Fielding, R. and L. Masinter, "Uniform Resource
        Identifiers (URI): Generic Syntax", RFC 2396, August 1998.

   [2]  WorldWideWeb Consortium, "Extensible Markup Language (XML) 1.0
        (Second Edition)", W3C Recommendation, October 2000,

   [3]  WorldWideWeb Consortium, "Namespaces in XML", W3C
        Recommendation, January 1999, <

   [4]  WorldWideWeb Consortium, "XML Schema Part 0: Primer", W3C
        Recommendation, May 2001, <>.

   [5]  WorldWideWeb Consortium, "Resource Description Framework (RDF)
        Model and Syntax Specification", W3C Recommendation, February

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        1999, <>.

   [6]  Mealling, M., Masinter, L., Hardie, T. and G. Klyne, "An IETF
        URN Sub-namespace for Registered Protocol Parameters", draft-
        mealling-iana-urn-02.txt (work in progress), August 2001.

Author's Address

   Michael Mealling
   VeriSign, Inc.

   Mountain View, CA


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