[uriMediaType-9] Dear IETF ...


The W3C  tech arch group  http://www.w3.org/2001/tag
has been considering the issues which
have come up relating to transitioning MIME types to URIs. See


for our finding in this area.

This an issue which Don, you addresses in your draft (referenced below)
How should we follow up and make this happen?

We need to move to get the IANA folks to not only allocate persistent
HTTP   URIs but also have a web server run so that information can be
found by dereferencing the URIs.

How can we achieve this?

Tim BL
chair, W3C-TAG

TAG Finding: Mapping between URIs and Internet Media Types
This version:
Stuart Williams
Copyright  2002 W3C (MIT, INRIA, Keio), All Rights Reserved. W3C
liability, trademark, document use and software licensing rules apply.


The question (see issue uriMediaType-9) that prompted this finding was "Why
does the Web use Internet media types and not URIs?" This finding documents
the TAG's opinion on the relationship between URIs and Internet Media Types
and proposes the establishment of a single, normative recommendation for
mapping between Internet media types [RFC2046] and URI [RFC2396].

Status of this document
This document has been produced by the W3C Technical Architecture Group
(TAG). The TAG approved this finding at its 8 April 2002 teleconference.

Additional TAG findings, both approved and in draft state, may also be
available. The TAG expects to incorporate this and other findings into a Web
Architecture Document that will be published according to the process of the
W3C Recommendation Track.

Please send comments on this finding to the publicly archived TAG mailing
list www-tag@w3.org (archive).

Relevant Principles of Web Architecture
All important resources should be identifiable by URI.
URI's for important resources should be dereferencable.
Dereferencing URI's for important abstract concepts (for example, Internet
protocol parameters) should return human and/or machine readable
representations that describe the nature and purpose of those resources.
Related Work
The W3C TAG is aware of:

A mapping between Internet media types and URI's under a new Content-Type:
URI scheme by Donald Eastlake [Eastlake]
A scheme for assiging URN's to important IETF protocol parameters including
Internet media types by the IETF Network Working Group [Iana-Urn] .
Mapping between Internet Media Types and URIs
The TAG regards Internet media types to be important resources that deserve
identification by URI.

Both Internet media types and URIs are used in various contexts for document
type labeling. The TAG supports the establishment of a single, normative
recommendation for mapping between Internet media types [RFC2046] and URIs

The TAG has a strong preference that URIs resulting from this mapping be
dereferenceable. The TAG requests that IANA, the authority which adminsters
the registry of Internet media types, be committed to providing persistent
and dereferencable URIs that return a document containing human and/or
machine readable information about the associated Internet media type,
including references to other sources of human readable and machine readable

Eastlake proposes a mapping to a new URI scheme, "Content-Type:", for which
there is no resolution or dereference mechanism, specified or deployed. The
IETF Network Working Group propose a mapping to URNs, which, in general,
cannot be dereferenced.

The TAG would prefer that dereferencable http: scheme URIs be assigned under
the authority of the body that maintains the Internet media type registry.

"Mapping Between MIME Types, Content-Types, and URIs", Eastlake, D.,
Internet Draft. Located at
"An IETF URN Sub-namespace for Registered Protocol Parameters", Mealling, M.
et al., IETF Network Working Group, Internet Draft. Located at
"Multipurpose Internet Mail Extensions (MIME) Part Two: Media Types", Freed,
N. et. al, IETF Network Working Group, RFC 2046. Located at
"Uniform Resource Identifiers (URI): Generic Syntax", Berners-Lee, T. et al,
IETF Network Working Group, RFC 2396. Located at


Received on Thursday, 23 May 2002 10:52:14 UTC