Network Working GroupA. Swartz
Expires: August 13, 2003February 12, 2003

application/rdf+xml Media Type Registration

Status of this Memo

This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026.

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Copyright (C) The Internet Society (2003). All Rights Reserved.


This document describes a media type (application/rdf+xml) for use with the 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. Discussion of this Document

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2. 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 properly.


3. application/rdf+xml Registration

This is a media type registration as defined in Multipurpose Internet Mail Extensions (MIME) Part Four: Registration Procedures[6]

MIME media type name: application

MIME subtype name: rdf+xml

Required parameters: none

Optional parameters: charset

Same as charset parameter of application/xml.

Encoding considerations:

Same as charset parameter of application/xml.

Security considerations:

Security considerations include many of those described in section 10 of RFC 3023[4] and more, due to the semantic nature of RDF. RDF documents may make assertions about anything and it is expected that future work with Digital Signature and "Web of Trust" will make it more clear how to build secure RDF systems.

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[3].

Published specification: see RDF/XML Syntax Grammar[1] and RDF Model Theory[2] (working drafts as of 2002-03) and the older RDF Model and Syntax[3]

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 "" to identify the RDF namespace. This will usually be towards the top of the document.

File extension(s): .rdf

Macintosh File Type Code(s): "TEXT"

For further information:

Dan Brickley <>

RDF Interest Group <>

More information may be found on the RDF website: <>

Intended usage: COMMON

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.


4. Social Context

When an RDF graph is asserted in the Web, its publisher is saying something about their view of the world. Such an assertion should be understood to carry the same social import and responsibilities as an assertion in any other format. A combination of social (e.g. legal) and technical machinery (protocols, file formats, publication frameworks) provide the contexts that fix the intended meanings of the vocabulary of some piece of RDF, and which distinguish assertions from other uses (e.g. citations, denials or illustrations).

The technical machinery includes protocols for transferring information (e.g. HTTP, SMTP) and file formats for encapsulating and labelling information (e.g. MIME, XML). This indicates the use of RDF/XML as distinct from some other XML that happens to look like RDF. Issuing an HTTP GET request and obtaining data with a "200 OK" response code is a technical indication that the received data was published at the request URI.

The social machinery includes the form of publication: publishing some unqualified statements on one's World Wide Web home page would generally be taken as an assertion of those statements. But publishing the same statements with a qualification, such as "here are some common myths", or as part of a rebuttal, would likely not be construed as an assertion of the truth of those statements. Similar considerations apply to the publication of assertions expressed in RDF.

An RDF graph may contain "defining information" that is opaque to logical reasoners. This information may be used by human interpreters of RDF information, or programmers writing software to perform specialized forms of deduction in the Semantic Web.


5. 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[5] 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.

However, in RDF, the thing identified by a URI with fragment identifier does not bear any particular relationship to the thing identified by the URI alone. This differs from some readings of the URI specification[5], so attention is recommended when creating new RDF terms which use fragment identifiers.


6. 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 [RDF]. 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 completed.


7. IANA Considerations

This document calls for registration of a new MIME content-type, according to the registration template in section 2.


8. Acknowledgements

Thanks to Dan Connolly for writing the first version of this draft[8], to Andy Powell for reminding us we needed one, to Marshall Rose for his xml2rfc converter, and to Graham Klyne, Jan Grant, and Dave Beckett for their helpful comments on early versions of this document.



[1] Beckett, D., "RDF/XML Syntax Specification (Revised)", W3C rdf-syntax-grammar, March 2002.
[2] Hayes, P., "RDF Model Theory", W3C rdf-mt, February 2002.
[3] Lassila, O. and R. Swick, "Resource Description Framework (RDF) Model and Syntax Specification", W3C REC-rdf-syntax, February 1999.
[4] Murata, M., St.Laurent, S. and D. Kohn, "XML Media Types", RFC 3023, January 2001.
[5] Berners-Lee, T., Fielding, R. and L. Masinter, "Uniform Resource Identifiers (URI): Generic Syntax", RFC 2396, August 1998.
[6] Freed, N., Klensin, J. and J. Postel, "Multipurpose Internet Mail Extensions (MIME) Part Four: Registration Procedures", BCP 13, RFC 2048, November 1996.
[7] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997.
[8] Connolly, D., "A media type for Resource Description Framework (RDF)", March 2001.


Author's Address

  Aaron Swartz
  349 Marshman
  Highland Park, IL 60035
Phone:  +1 847 432 8857


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