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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: Wed, 11 Feb 2009 12:46:24 -0800
To: Lachlan Hunt <lachlan.hunt@lachy.id.au>
CC: HTML WG <public-html@w3.org>
Message-ID: <8B62A039C620904E92F1233570534C9B0118C85ACA38@nambx04.corp.adobe.com>
> IIRC, I believe the issue is that the XHTML2 WG think they have change 
> control over that namespace URI and that we shouldn't be using it. 
> Additionally, the latest XHTML 2 editor's draft is now using the 
> namespace [1].

Two or more languages can use the same namespace if they're using the
same vocabulary, but it might be useful to have a separate
document that defines the namespace and points to the languages
that use it.

> This issue has been discussed in depth around mid 2007 [2].  The problem 
> is that XHTML5 and XHTML2 are completely incompatible with each other 
> and they cannot possibly use the same namespace as each other.

"incompatible" isn't the same as "completely incompatible". If the
vocabularies are mainly the same -- and they should be -- then each
incompatibility needs to be noted and we can move on.

> But XHTML2 also has several major incompatibilities with XHTML1, which 
> would effectively make it impossible to implement both XHTML 1.x and 2 
> in the same implementation, if they share the same namespace [3]. 

The fact that one language makes <title>abc</title> equivalent
to <meta property="title" content="Document Title"/> and the other
does not does mean the languages are incompatible. But the elements
"title" and "meta" have the same meaning as vocabulary items, their
usage is different in the two languages.

I know that there is significant resistance to the idea that you might
define a vocabulary independent of a language which uses that vocabulary,
or that you might define a language independent of the processing rules
by which instances of text in the language should be processed, but
those separations are fundamental to the design of XML, and the question
here is about XML namespaces and their use.

> XHTML 5, on the other hand, has not only been designed with compatibility
> in mind, 

I'm not sure this point (what was "in mind" when the language was
designed) is relevant; what's important is whether there actually
*is* compatibility, no?

> success is dependent upon continuing to use the same namespace.

Again, I’m not sure this is relevant, but I don't think it's clear
that "success of HTML5" depends on "success of XHTML5", or that
"success of XHTML5" depends on "use of the same namespace".

> Basically, the only solution to this issue that should be considered is 
> that we continue using the namespace and the XHTML2 WG use a different 
> namespace.

It is not a useful style of argument to assert that the only
solution that should be *considered* is the one you favor.
Certainly there are other solutions that should be considered,
such as using the same namespace and resolving any compatibility
issues that might otherwise arise.

> Otherwise, I will propose closing the issue.

> Absolutely, keeping this issue open is unnecessary.  The issue is 
> entirely political, with no technical justification for us to keep it 
> open.  It should be closed immediately.  At most, a separate issue 
> should be raised with the XHTML2 WG to make them use an alternative 
> namespace.

That isn't what I propose, actually; what I propose is continuing
to use the same namespace, but resolving any vocabulary incompatibilities,
(not language or processing rule incompatibilities, note) either
by changing XHTML5 or XHTML2 to remove the vocabulary incompatibility,
or renaming the element or attribute name in one or the other to
remove the vocabulary incompatibility.

Note that "incompatibility" 
[1] http://www.w3.org/MarkUp/2009/ED-xhtml2-20090205/conformance.html#strict


[3] http://lists.w3.org/Archives/Public/public-html/2007Jun/0700.html 
(This has a list of issues with XHTML2, including several that cause 
incompatibilities with the namespace.)

Lachlan Hunt - Opera Software


Received on Wednesday, 11 February 2009 20:47:09 UTC

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