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Re: Media types and versioning

From: John Cowan <cowan@ccil.org>
Date: Tue, 22 May 2007 16:29:36 -0400
To: Jan Algermissen <algermissen1971@mac.com>
Cc: noah_mendelsohn@us.ibm.com, Mark Baker <distobj@acm.org>, David Orchard <dorchard@bea.com>, Marc de Graauw <marc@marcdegraauw.com>, mark@coactus.com, Marc de Graauw <mdegraau@xs4all.nl>, www-tag@w3.org
Message-ID: <20070522202936.GG32416@mercury.ccil.org>

Jan Algermissen scripsit:

> This could be rephrased to "what are the allowed variations between
> two versions of a format if they are to remain the same media type?".

> Has that ever been thought through?

RFC 2045 says:

   It is also worth noting that version control for specific media types
   is not accomplished using the MIME-Version mechanism.  In particular,
   some formats (such as application/postscript) have version numbering
   conventions that are internal to the media format.  Where such
   conventions exist, MIME does nothing to supersede them.  Where no
   such conventions exist, a MIME media type might use a "version"
   parameter in the content-type field if necessary.

and likewise

   The purpose of the Content-Type field is to describe the data
   contained in the body fully enough that the receiving user agent can
   pick an appropriate agent or mechanism to present the data to the
   user, or otherwise deal with the data in an appropriate manner. The
   value in this field is called a media type.

That's all the guidance we get.

-- 
In politics, obedience and support      John Cowan <cowan@ccil.org>
are the same thing.  --Hannah Arendt    http://www.ccil.org/~cowan
Received on Tuesday, 22 May 2007 20:29:59 GMT

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