text/html for html and xhtml (Was: Supporting MathML and SVG in text/html, and related topics)

Previously:

  Yes, but the point is, once a user agent begins to sniff, there's no
  rational excuse for it not to recognize compliant xhtml+(mathml|svg).

  >> What obstacles to this exist?
  >
  > The Web.

  Really!?!


And then:

>>> The Web.
>>
>> Really!?!
>
> Yes, see for instance:
>
>    http://lists.w3.org/Archives/Public/public-html/2007Aug/1248.html

Taylor's comment is mainly about what happens when a user agent
confuses tag soup with good xhtml.

It is a different question how a user agent decides what it is looking
at.

Whether there is one mimetype or two, erroneous content will need
handling.  The experiment begun around 2001 of "punishing" bad
documents in application/xhtml+xml seems to have led to that mime type
not being much used.

So user agents need to learn how to recognize the good and the bad
in both mimetypes.

Otherwise you have Gresham's Law: the bad documents will drive out the
good.

The logical way to go might be this:

If it has a preamble beginning with "^<?xml " or a sensible
xhtml DOCTYPE declaration or a first element "<html xmlns=...>",
then handle it as xhtml unless and until it proves to be non-compliant
xhtml (e.g, not well-formed xml, unquoted attributes, munged handling
of xml namespaces, ...).  At the point it proves to be bad xhtml reload
it and treat it as "regular" html.

So most bogus xhtml will then be 1 or 2 seconds slower than good xhtml.
Astute content providers will notice that and then do something about it.
It provides a feedback mechanism for making the web become better.

                                    -- Bill

Received on Thursday, 17 April 2008 04:41:42 UTC