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