The IETF XML Registry
RFC 3688

Document Type RFC - Best Current Practice (January 2004; No errata)
Also known as BCP 81
Was draft-mealling-iana-xmlns-registry (individual in app area)
Author Michael Mealling 
Last updated 2013-03-02
Stream Internet Engineering Task Force (IETF)
Formats plain text html pdf htmlized (tools) htmlized bibtex
Stream WG state (None)
Document shepherd No shepherd assigned
IESG IESG state RFC 3688 (Best Current Practice)
Action Holders
Consensus Boilerplate Unknown
Telechat date
Responsible AD Ted Hardie
Send notices to <>
Network Working Group                                        M. Mealling
Request for Comments: 3688                                VeriSign, Inc.
BCP: 81                                                     January 2004
Category: Best Current Practice

                         The IETF XML Registry

Status of this Memo

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

Copyright Notice

   Copyright (C) The Internet Society (2004).  All Rights Reserved.


   This document describes an IANA maintained registry for IETF
   standards which use Extensible Markup Language (XML) related items
   such as Namespaces, Document Type Declarations (DTDs), Schemas, and
   Resource Description Framework (RDF) Schemas.

1.  Introduction

   Over the past few years, the Extensible Markup Language (XML)
   [W3C.REC-xml] has become a widely used method for data markup.  There
   have already been several IETF Working Groups that have produced
   standards that define XML Document Type Definitions (DTDs), XML
   Namespaces [W3C.REC-xml-names], and XML Schemas [W3C.REC-xmlschema-
   1]. Each one of these technologies uses Uniform Resource Identifiers
   (URIs) [RFC2396] and other standardized identifiers to identify
   various components.

   For example, while it has been the practice within some standards
   that use Document Type Definitions (DTDs) to forego the use of the
   PUBLIC identifiers in favor of 'well known' SYSTEM identifiers, it
   has proven to be more trouble than its worth to attempt to
   standardize SYSTEM identifiers.  The result is that several IETF
   standards that have simply created non-resolvable URIs in order to
   simply identify but not resolve the DTD for some given XML document.

   This document seeks to standardize and improve these practices by
   creating an IANA maintained registry of XML element identifiers so
   that document authors and implementors have a well maintained and

Mealling                 Best Current Practice                  [Page 1]
RFC 3688                 The IETF XML Registry              January 2004

   authoritative location for their XML elements.  As part of this
   standard, the IANA will maintain:

   o  the public representation of the document,

   o  the URI for the elements if one is provided at the time of

   o  a registry of Public Identifiers as URIs.

   In the case where the registrant does not request a particular URI,
   the IANA will assign it a Uniform Resource Name (URN) that follows

2.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   document are to be interpreted as described in BCP 14, RFC 2119

3.  Registerable Documents

3.1.  The Assigned/Registered URI

   All elements (except PUBLIC identifiers) 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
   consensus process.  Basically, this means that it must be documented
   in a RFC.  The RFC 3553 [RFC3553] URN registration template is found
   in Section 6.

   The IANA will also maintain a file server available via at least HTTP
   and FTP 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.

Mealling                 Best Current Practice                  [Page 2]
RFC 3688                 The IETF XML Registry              January 2004

   Implementors are warned that they should not programatically rely on
   those resources being available or the directory structure remaining
   static for any reason.  It is explicitly recognized that some
   software tools attempt to download DTDs, schema, etc., 'on the fly'
   and that developers should understand when this is done and when to
   not reference IANA network resources as a 'schema download
   repository'.  This is the reason that the IANA will not register or
   provide SYSTEM identifiers.

3.2.  Registerable Classes

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

   publicid -- An XML document that contains a DOCTYPE declaration or
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