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Re: [XHTML1.1] Error in Conformance Definition document?

From: Jukka K. Korpela <jkorpela@cs.tut.fi>
Date: Mon, 2 Apr 2007 09:30:31 +0300 (EEST)
To: www-html@w3.org
Message-ID: <Pine.GSO.4.64.0704020858290.29843@mustatilhi.cs.tut.fi>

On Mon, 2 Apr 2007, Kelly wrote:

> I wanted to mention this, because I just had it pointed to as proof that W3C
> wants people to violate their own conformance instructions and serve XHTML
> using text/html regardless of version.
>
> http://www.w3.org/TR/xhtml11/conformance.html#strict

Well, pobody's nerfect, and that W3C document surely violates W3C 
recommendations, specifically WAI guidelines (WCAG 1.0), by using
dark orange background for black and even red text (insufficient color 
contrast). Use of color only might be acceptable if it does not convey any 
essential information but is only a way to express visually something that 
is expressed in text too (though it is not obvious what that is).

But regarding the media type information issue that you're raising, the 
definitions are so vague that it would be difficult to violate their 
conformance criteria. It's easy to violate the rules of clarity and 
understandability, though.

> Is there a reason the last paragraph of that section says you can serve XHTML
> 1.1 as text/html, and then proceeds to link to a document that says you can't
> (the XHTML MIME type document)?

I guess the reason was that a link to a relatively old document was added 
just to help people find more detailed explanations and examples. Probably 
the content of the document was not scrutinized when the link was added.

The URL http://www.w3.org/TR/xhtml11/ refers to whatever W3C treats as the 
"latest version of XHTML 1.1". Today this seems to be
http://www.w3.org/TR/2007/WD-xhtml11-20070216
which calls itself "Working Draft". This is somewhat strange, since there 
_is_ a W3C Recommendation on XHTML 1.1,
http://www.w3.org/TR/2001/REC-xhtml11-20010531/

So if we start from the recommendation, we find that it is a stable 
document and the official W3C recommendation, yet contains an indication 
of the URL of the "latest version" - pointing to an unstable document. 
There must be a good explanation to this, but it's still very confusing to 
people, even if they have been told to follow the "latest W3C 
specifications".

The statement "XHTML 1.1 documents SHOULD be labeled with the Internet 
Media Type text/html as defined in [RFC2854] or application/xhtml+xml as 
defined in [RFC3236]." is apparently meant to change the policy. 
Previously, application/xhtml+xml was clearly favored for XHTML, although 
text/html was allowed for specific purposes (and it is hard to see how 
XHTML 1.1 documents could fit into this, especially since XHTML 1.1 has 
nothing resembling appendix C of XHTML 1.0). Now both are mentioned with 
no expressed preference, and text/html is mentioned first!

Formally there is no problem in referring, in a draft for a _normative_
document, to an _informative_ document that contradicts the normative 
document in some way, or at least has a different tone of voice. Note that 
the reference says: "For further information on using media types with 
XHTML, see the informative note [XHTMLMIME]." It's an _informative_ 
(non-normative) reference if I ever saw one.

Pragmatically, this leaves us in a land of confusion. The [XHTMLMIME] 
document even says:

"XHTML documents served as 'text/html' will not be processed as XML 
[XML10], e.g. well-formedness errors may not be detected by user agents. 
Also be aware that HTML rules will be applied for DOM and style sheets 
(see C.11 and C13 of [XHTML1] respectively)."

As far as I can see, such processing violates XHTML rules, since they 
don't allow such exceptions. The draft XHTML 1.1 does not even allude to 
such things, except via the link we're discussing. Again, formally there 
is no problem. An informative document may say just anything without 
formally affecting a normative document that refers to it.

Just in case there is no intended policy change, the statement might need 
rewording. For example:

"XHTML 1.1 documents SHOULD be labeled with the Internet Media Type 
application/xhtml+xml as defined in [RFC3236]. If they are labeled with
text/html as defined in [RFC2854], user agents are not required to follow 
the processing rules in this specification. For further information on 
using media types with XHTML, see the informative note [XHTMLMIME]."

-- 
Jukka "Yucca" Korpela, http://www.cs.tut.fi/~jkorpela/
Received on Monday, 2 April 2007 06:30:34 GMT

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