W3C | TAG | TAG Work Plan

TAG Product: MIME architecture for the Web


On its teleconference of 2 February 2012, the TAG resolved that: The TAG is closing its work on MIME/Web, noting successful completion of 1st round of work. Product priority list to be updated after closing product page approved. On 3 May 2012 the TAG approved this version of the product page.


Work on this topic proceeded in two phases. During the first, Larry Masinter prepared an analysis that led to extensive TAG discussion over a period of more than a year. The result of this was a series of IETF Internet Drafts, the latest of which, as of 29 April 2012, is http://tools.ietf.org/html/draft-masinter-mime-web-info-02, now expired. Larry and others also had extensive interactions with IETF groups responsible for, e.g., updating registration procedures for media types.

The TAG then considered doing a second round of work in this area, but as noted in the resolution above, it was decided that sufficient progress is being made at IETF that a formal TAG "product" in this area is not needed, at least for now. Accordingly, the TAG notes the successful completion of the first round of work, and the decision not now to proceed further.

The "Success criteria" section below lists several requirements that the TAG work on this topic did not accomplish, except insofar as some of the topics of interest were discussed in the Internet Draft:

  1. The TAG did not "... publish analyses explaining ... " or suggest many concrete steps for resolving problems. TAG members wrote and reviewed documents, but didn't "publish" it in any way that is listed as a TAG product.
  2. The TAG only partially succeeded at "liase with the IETF and other concerned parties to resolve these issues", as there are several topics we have not explored, and we did not meet with IETF parties to effect a liaison on these topics.
  3. The TAG didn't "document the solutions ..." or "highlight areas in which unsolved problems remain".

Ongoing work

Although the TAG has formally closed its work on this "product", work is ongoing in several related areas:

The sections below discuss the goals that would have applied to the second round of work, had it been completed.


There are a number of issues that need to be addressed to insure careful evolution of the Web while retaining global interoperability. Many issues revolve around providing for extensibility of stable specifications for languages and protocols by using an extensible set of identifiers; one common way of managing identifiers and their meaning is by use of a registry. The Internet mail framework MIME (Multipurpose Internet Mail Exchange) was designed to facilitate extensibility in the Internet mail infrastructure, and the Web adopted several of the MIME mechanisms for use in HTTP in other protocols. In particular, MIME's registry of names of languages and file formats (Internet Media Types), and its registry of character sets (charsets) are used in many of the Web's protocols and formats.


The goal of this activity is to help guide the use of MIME protocol elements in Web specifications and implementations, and to analyze, document, and propose solutions to difficulties with current effective use of MIME in the Web. This activity is one of several key developments in helping the community manage extensibility securely and reliably.

Success criteria

Key deliverables with dates:


TAG Members assigned:

TAG Issues, Actions and Tracker Product Page



Tracker Product Page

Available versions of this document:

Latest: http://www.w3.org/2001/tag/products/mimeweb.html

This version: http://www.w3.org/2001/tag/products/mimeweb-2012-05-03.html

Previous versions: http://www.w3.org/2001/tag/products/mimeweb-2012-04-30.html, http://www.w3.org/2001/tag/products/mimeweb-2012-04-29.html, http://www.w3.org/2001/tag/products/mimeweb-2011-12-24.html, http://www.w3.org/2001/tag/products/mimeweb-2011-12-21.html http://www.w3.org/2001/tag/products/mimeweb-2011-08-23.html, http://www.w3.org/2001/tag/products/mimeweb-2011-08-04.html