Re: Requiring charset parameter on +xml types?

Hello Mark,

As far as I understand, for text/...+xml, the charset parameter
is very close to being required (by using the general MIME default
of us-ascii, which overrides any internal information).
For application/...+xml (or others such as image/...+xml), the
internal information is relevant if there is no charset parameter.

To solve the problems, the following things should help:

- Help to make system administrators, webmasters, and so on,
   aware of the fact that they have to allow settings and have
   to make them.
- Maybe to define a type application/html+xml for use by those
   people who want to just ship files around.
- For text/html+xml (and that would work for all types, actually),
   beef up the servers so that they can use the information in the
   file to set the charset parameter correctly.
   [Sorry to be a bit lengthy here, but I just almost got excited
    about this idea.]
   This would work about as follows:
   - Server detects that content type of outgoing stuff is +xml.
   - Server verifies that there is no setting for the charset
     parameter in the configuration.
   - Server peeks into the data to check for a BOM and/or for an
     encoding declaration.
   - Server sets charset parameter.

   Please note the following:
   - If this feature is introduced into a server without any
     configuration options, the only potentially undesirable
     effect is to label files that were intended to go out
     as defaulted to us-ascii as utf-8 explicitly. But this
     is in no way a problem, because every us-ascii file is
     a utf-8 file (this means no wrong labels), and because
     the chance that a receiving XML processor understands
     utf-8 are higher than for us-ascii (utf-8 is required,
     us-ascii is not).
   - Such a feature has been the idea behind <meta http-equiv,
     but it turned out that the lookahead length and processing
     effort for that is much too high. For the xml encoding
     declaration, things look much better.

Regards,   Martin.

At 00/10/13 13:52 -0400, Mark Baker wrote:
>Greetings,
>
>At the HTML WG f2f yesterday, it was proposed that we should require the
>use of the charset parameter on the XHTML media type.  This came up in
>the discussion over whether the media type should use application/ or
>text/.
>
>Would requiring this parameter help solve the problem of those broken
>web servers that I've heard about that mislabel non-US-ASCII encoded
>text/* content as US-ASCII?
>
>Are the any other issues/pros/cons we should be aware of for requiring
>this parameter?
>
>Thanks.
>
>BTW, for W3C members that are interested (i.e. it's not required reading
>to grok this message - mustUnderstand = 0 :-), the IRC log of the
>conversation is available at;
>
>http://lists.w3.org/Archives/Member/w3c-html-wg/2000OctDec/0104.html
>
>MB