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Network Working Group                                          A. Swartz
Request for Comments: 3870                                   AaronSw.com
Category: Informational                                   September 2004

              application/rdf+xml Media Type Registration

Status of this Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard of any kind.  Distribution of this
   memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2004).


   This document describes a media type (application/rdf+xml) for use
   with the Extensible Markup Language (XML) serialization of the
   Resource Description Framework (RDF).  RDF is a language designed to
   support the Semantic Web, by facilitating resource description and
   data exchange on the Web.  RDF provides common structures that can be
   used for interoperable data exchange and follows the World Wide Web
   Consortium (W3C) design principles of interoperability, evolution,
   and decentralization.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  2
   2.  application/rdf+xml Registration . . . . . . . . . . . . . . .  2
   3.  Fragment Identifiers . . . . . . . . . . . . . . . . . . . . .  4
   4.  Historical Considerations  . . . . . . . . . . . . . . . . . .  4
   5.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . .  4
   6.  Security Considerations  . . . . . . . . . . . . . . . . . . .  5
   7.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . .  5
   8.  References . . . . . . . . . . . . . . . . . . . . . . . . . .  6
       8.1.  Normative References . . . . . . . . . . . . . . . . . .  6
       8.2.  Informative References . . . . . . . . . . . . . . . . .  6
   9.  Author's Address . . . . . . . . . . . . . . . . . . . . . . .  7
   10. Full Copyright Statement . . . . . . . . . . . . . . . . . . .  8

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RFC 3870                  application/rdf+xml             September 2004

1. Introduction

   RDF is a language designed to support the Semantic Web, by
   facilitating resource description and data exchange on the Web.  RDF
   provides common structures that can be used for interoperable data
   exchange and follows the W3C design principles of interoperability,
   evolution, and decentralization.

   While the RDF data model [2] can be serialized in many ways, the W3C
   has defined the RDF/XML syntax [1] to allow RDF to be serialized in
   an XML format.  The application/rdf+xml media type allows RDF
   consumers to identify RDF/XML documents so that they can be processed

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   document are to be interpreted as described in BCP 14, RFC 2119 [6].

2. application/rdf+xml Registration

   This is a media type registration as defined in RFC 2048,
   "Multipurpose Internet Mail Extensions (MIME) Part Four: Registration
   Procedures" [5].

      MIME media type name: application

      MIME subtype name: rdf+xml

      Required parameters: none

      Optional parameters: charset

         Same as charset parameter of application/xml, defined in RFC
         3023 [4].

      Encoding considerations:

         Same as charset parameter of application/xml, defined in RFC
         3023 [4].

      Security considerations:

         See "Security Considerations" (Section 6).

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RFC 3870                  application/rdf+xml             September 2004

      Interoperability considerations:

         It is RECOMMENDED that RDF documents follow the newer RDF/XML
         Syntax Grammar [1] as opposed to the older RDF Model and Syntax
         specification [7].

         RDF is intended to allow common information to be exchanged
         between disparate applications.  A basis for building common
         understanding is provided by a formal semantics [3], and
         applications that use RDF should do so in ways that are
         consistent with this.

      Published specification:

         see RDF/XML Syntax Grammar [1] and RDF: Concepts and Abstract
         Syntax [2] and the older RDF Model and Syntax [7]

      Applications which use this media type:

         RDF is device-, platform-, and vendor-neutral and is supported
         by a range of Web user agents and authoring tools.

      Additional information:

         Magic number(s): none

            Although no byte sequences can be counted on to consistently
            identify RDF, RDF documents will have the sequence
            "http://www.w3.org/1999/02/22-rdf-syntax-ns#" to identify
            the RDF namespace. This will usually be towards the top of
            the document.

      File extension(s): .rdf

      Macintosh File Type Code(s): "rdf "

      For further information:

         Dan Brickley <danbri@w3.org>

         RDF Interest Group <www-rdf-interest@w3.org>

         More information may be found on the RDF website:


      Intended usage: COMMON

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RFC 3870                  application/rdf+xml             September 2004

      Author/Change controller:

         The RDF specification is a work product of the World Wide Web
         Consortium.  The W3C and the W3C RDF Core Working Group have
         change control over the specification.

3.  Fragment Identifiers

   The rdf:ID and rdf:about attributes can be used to define fragments
   in an RDF document.

   Section 4.1 of the URI specification [8] notes that the semantics of
   a fragment identifier (part of a URI after a "#") is a property of
   the data resulting from a retrieval action, and that the format and
   interpretation of fragment identifiers is dependent on the media type
   of the retrieval result.

   In RDF, the thing identified by a URI with fragment identifier does
   not necessarily bear any particular relationship to the thing
   identified by the URI alone.  This differs from some readings of the
   URI specification [8], so attention is recommended when creating new
   RDF terms which use fragment identifiers.

   More details on RDF's treatment of fragment identifiers can be found
   in the section "Fragment Identifiers" of the RDF Concepts document

4.  Historical Considerations

   This media type was reserved in RFC 3023 [4], saying:

      RDF documents identified using this MIME type are XML documents
      whose content describes metadata, as defined by [7].  As a format
      based on XML, RDF documents SHOULD use the '+xml' suffix
      convention in their MIME content-type identifier.  However, no
      content type has yet been registered for RDF and so this media
      type should not be used until such registration has been

5.  IANA Considerations

   This document calls for registration of a new MIME media type,
   according to the registration in Section 2.

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RFC 3870                  application/rdf+xml             September 2004

6.  Security Considerations

   RDF is a generic format for exchanging application information, but
   application designers must not assume that it provides generic
   protection against security threats.  RFC 3023 [4], section 10,
   discusses security concerns for generic XML, which are also
   applicable to RDF.

   RDF data can be secured for integrity, authenticity and
   confidentiality using any of the mechanisms available for MIME and
   XML data, including XML signature, XML encryption, S/MIME, OpenPGP or
   transport or session level security (e.g., see [9], especially
   sections 3.4, 3.5, 3.10, [10], [11], [12]).

   RDF is intended to be used in documents that may make assertions
   about anything, and to this end includes a specification of formal
   semantics [3].  The semantics provide a basis for combining
   information from a variety of sources, which may lead to RDF
   assertions of facts (either by direct assertion, or via logical
   deduction) that are false, or whose veracity is unclear.  RDF
   application designers should not omit consideration of the
   reliability of processed information.  The formal semantics of RDF
   can help to enhance reliability, since RDF assertions may be linked
   to a formal description of their derivation.  There is ongoing
   exploration of mechanisms to record and handle provenance of RDF
   information.  As far as general techniques are concerned, these are
   still areas of ongoing research, and application designers must be
   aware, as always, of "Garbage-in, Garbage-out".

7.  Acknowledgements

   Thanks to Dan Connolly for writing the first version of this document
   [13], to Andy Powell for <http://www.w3.org/2000/03/rdf-
   tracking/#mime-types-for-rdf-docs>, to Marshall Rose for his
   <http://xml.resource.org/> converter, and to Graham Klyne, Jan Grant,
   and Dave Beckett for their helpful comments on early versions of this

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RFC 3870                  application/rdf+xml             September 2004

8.  References

8.1.  Normative References

   [1]  Beckett, D., "RDF/XML Syntax Specification (Revised)", W3C rdf-
        syntax-grammar, February 2004, <http://www.w3.org/TR/2004/REC-

   [2]  Klyne, G. and J. Carroll, "Resource Description Framework (RDF):
        Concepts and Abstract Syntax", W3C rdf-concepts, February 2004,

   [3]  Hayes, P., "RDF Model Theory", W3C rdf-mt, February 2004,

   [4]  Murata, M., St.Laurent, S. and D. Kohn, "XML Media Types", RFC
        3023, January 2001.

   [5]  Freed, N., Klensin, J. and J. Postel, "Multipurpose Internet
        Mail Extensions (MIME) Part Four: Registration Procedures", BCP
        13, RFC 2048, November 1996.

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

8.2.  Informative References

   [7]  Lassila, O. and R. Swick, "Resource Description Framework (RDF)
        Model and Syntax Specification", W3C REC-rdf-syntax, February
        1999, <http://www.w3.org/TR/REC-rdf-syntax>.

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

   [9]  Bellovin, S., Schiller, J. and C. Kaufman, Eds., "Security
        Mechanisms for the Internet", RFC 3631, December 2003.

   [10] Rescorla, E., "HTTP Over TLS", RFC 2818, May 2000.

   [11] Eastlake, D., Reagle, J. and D. Solo, "(Extensible Markup
        Language) XML-Signature Syntax and Processing", RFC 3275, March

   [12] Eastlake, D. and J. Reagle, "XML Encryption Syntax and
        Processing", W3C xmlenc-core, December 2002,

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   [13] Connolly, D., "A media type for Resource Description Framework
        (RDF)", March 2001, <http://www.w3.org/2001/03mr/rdf_mt>.

9.  Author's Address

   Aaron Swartz
   349 Marshman
   Highland Park, IL  60035

   Phone: +1 847 432 8857
   EMail: me@aaronsw.com
   URI:   http://www.aaronsw.com/

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RFC 3870                  application/rdf+xml             September 2004

10.  Full Copyright Statement

   Copyright (C) The Internet Society (2004).

   This document is subject to the rights, licenses and restrictions
   contained in BCP 78, and at www.rfc-editor.org, and except as set
   forth therein, the authors retain all their rights.

   This document and the information contained herein are provided on an

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