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Re: Note on DTD-related questions

From: MURATA Makoto <muraw3c@attglobal.net>
Date: Sat, 17 Jun 2000 04:24:05 +0900
Message-Id: <200006161924.AA00251@makoto.attglobal.net>
To: w3c-xml-schema-ig@w3.org
Cc: Murray Altheim <altheim@eng.sun.com>, www-xml-schema-comments@w3.org

 >That seems like a hasty conclusion. I have been working
 >on the details of various modularization issues
 >(in http://www.w3.org/XML/2000/04schema-hacking/), and I have
 >not found any of them to be insurmountable. I am
 >pretty close to being able to convert the XHTML DTD modules
 >to schema syntax by machine.

I had a look at your www site, but have not been able find an example of 
schemata containing more than one vocabulary.  What is the schema for 
your example "xhtml-mathml-ex.html"?

 >> This is a common requirement
 >> that is not satisfied (as far as I can understand from the
 >> Structures spec and the "Note on DTD-related questions".
 >Is it really a common requirement to be able to arbitrarily
 >override a content model this way? i.e. are DTDs really
 >used to represent contracts that are that weak?

Good question.

I think that the HTML WG and the XML Schem WG should try to 
clarify the requirements first.  Without this step, XML Schema 
cannot provide a basis for the integration of XHTML and other 
XML-based vocabularies being developed at W3C, in my opinion.  
I raised this issue once, but got ignored.

I can think of many scenarios.  Which is the scenario of the 
XML Schema WG and which is the scenario of the HTML WG?

1) A module never overrides content models in another module
   (In my understanding, this is the position of XML Schema.)

2) Each module freely overrides content models in another module.

3) Each module overrides content models in another module in a (set-theoretically) 
   upper-compatible manner.

4) Each module overrides content models in another module in a (set-theoretically) 
   upper-compatible manner by adding element types of foreign namespaces.

 >If a langauge designer intends that sort of weak contract,
 >they can express it using <any/>, no?

No.  Murray might want to allow a single preface element and allot 
<p> elements only in it.


MURATA Makoto  muraw3c@attglobal.net
Received on Friday, 16 June 2000 15:23:15 UTC

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