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RE: What's the problem? "Reuse of 1998 XHTML namespace is potentially misleading/wrong"

From: Larry Masinter <masinter@adobe.com>
Date: Mon, 16 Feb 2009 16:31:27 -0800
To: Karl Dubost <karl+w3c@la-grange.net>, Maciej Stachowiak <mjs@apple.com>
CC: Lachlan Hunt <lachlan.hunt@lachy.id.au>, HTML WG <public-html@w3.org>
Message-ID: <8B62A039C620904E92F1233570534C9B0118C8659009@nambx04.corp.adobe.com>
Thanks for the additional background. Much of this information
isn't readily linked to the issues page.

It seems that the XHTML namespace issue is quietly linked
to the issue of "when ATOM and XMPP refer to XHTML, which
language/dialect do they mean".

Karl quoted the Atom format and the XMPP format.

XMPP seems to recognize XHTML 2.0 but not XHTML5:
http://xmpp.org/extensions/xep-0071.html#w3c-versions
"The W3C is actively working on XHTML 2.0 [29] and may produce additional versions of XHTML in the future. This specification addresses XHTML 1.0 only, but it may be superseded or supplemented in the future by a XMPP Extension Protocol specification that defines methods for encapsulating XHTML 2.0 content in XMPP."

Atom only cites XHTML modularization
   [XHTML]    Altheim, M., Boumphrey, F., McCarron, S., Dooley, S.,
              Schnitzenbaumer, S., and T. Wugofski, "Modularization of
              XHTML[TM]", W3C REC REC-xhtml-modularization-20010410,
              April 2001, <http://www.w3.org/TR/2001/
              REC-xhtml-modularization-20010410>.

but there is no corresponding XHTML5 modularization,
and I wouldn't expect Atom to automatically upgrade
to XHTML5 without some update to the ATOM spec to 
clarify which language was meant by type="xhtml",
and otherwise for it to be restricted to XHTML 1.0.

So I'm unclear how those references add any light. Yes there are other specifications that rely on XHTML being a single language, and it is unfortunate that W3C has two groups chartered to produce different specs as an outgrowth of XHTML1.0. Yes, they will have to choose, if W3C doesn't.

Both XMPP/Jabber and Atom define which version of which specifications they make reference to in their specifications. Both could choose to update their references to XHTML5, to XHTML2, or to both (selected by some versioning mechanism either endorsed by W3C or independently invented by their embedding contexts), or to neither (leaving both at XHTML 1.0).

How does this affect the namespace or versioning issue, though?

Larry
--
http://larry.masinter.net


-----Original Message-----
From: Karl Dubost [mailto:karl+w3c@la-grange.net] 
Sent: Monday, February 16, 2009 4:14 PM
To: Maciej Stachowiak
Cc: Larry Masinter; Lachlan Hunt; HTML WG
Subject: Re: What's the problem? "Reuse of 1998 XHTML namespace is potentially misleading/wrong"


Le 17 févr. 2009 à 04:23, Maciej Stachowiak a écrit :
>> So I would propose instead:
>> a)  XHTML5 *MUST NOT* be used in arbitrary generic XML compound  
>> documents. Any
>>  use of the namespace in such contexts denotes XHTML2, not XHTML5.
>>  Since HTML5 and XHTML5 are not being designed for inclusion in  
>> arbitrary
>>  XML compound documents, this should not have any impact in practice.
>
> Since this proposal is based on a false premise I do not think it is  
> viable. Further, since user agents in practice support XHTML  
> namespace elements in arbitrary XML compound documents, this would  
> amount to requiring XHTML5 user agents to implement XHTML2, which is  
> not a reasonable requirement.


It has consequences already. The namespace is used in other formats  
such as

1. [Atom Syndication Format][1]
The reference given for the namespace/xhtml markup is [Modularization  
of XHTML][2]

    3.1.1.3. XHTML
    If the value of "type" is "xhtml", the content
    of the Text construct MUST be a single XHTML div
    element [XHTML] and SHOULD be suitable for
    handling as XHTML. The XHTML div element itself
    MUST NOT be considered part of the content. Atom
    Processors that display the content MAY use the
    markup to aid in displaying it. The escaped
    versions of characters such as "&" and ">"
    represent those characters, not markup.



2. [XMPP XHTML-IM][3]

    XMPP references also Modularization of XHTML.

    4. Concepts and Approach
    However, this <html/> element is used solely as
    a "wrapper" for the XHTML content itself, which
    content is encapsulated via one or more <body/>
    elements qualified by the
    'http://www.w3.org/1999/xhtml' namespace, along
    with appropriate child elements thereof.

http://www.ietf.org/rfc/rfc4287.txt 



[1]: http://tools.ietf.org/html/rfc4287#section-3.1.1.3
[2]: http://tools.ietf.org/html/rfc4287#ref-XHTML
[3]: http://xmpp.org/extensions/xep-0071.html 

-- 
Karl Dubost
Montréal, QC, Canada
http://twitter.com/karlpro
Received on Tuesday, 17 February 2009 00:32:10 GMT

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