Re: [xsl] Is there a XSL XSD?

[Wendell Piez <wapiez@xxxxxxxxxxxxxxxx>]

Hi George,

To be fair to the Working Group, one of the things you're missing is that a 
DTD doesn't "unambiguously define" very much at all ... it's limited to 
expressing not much more than the allowed structural relations among a 
finite set of element types. This is crucial, but it's not everything: the 
permissible syntax of attribute values, for example -- a critical part of 
XSL -- goes almost entirely beyond the expressive power of DTD syntax. A 
syntactically correct XSLT transform could present any of an unbounded set 
of element and attribute types (since it can have literal result elements) 
-- not to mention an attribute syntax of its own (XPath expressions and 
patterns, etc.).

Limit it to "pure" XSL (only xslt and fo namespaces) and things are 
somewhat better, though not much. Schema validation (XSD) is better able 
than DTD syntax to account for a number of the syntactic constraints -- but 
it's just been finished, whereas development of XSL has been going on since 
1998 (or late 1997 if you want to go back to the first W3C Note).

A non-normative DTD fragment describing an XSLT transform appears as 
Appendix C of the XSLT spec. Perhaps the final version of XSL will contain 
something like the DTD that RenderX have cooked up on the FO side (oh dear, 
it looks like I'm slipping into a British collective plural): I guess it 
never hurts to ask.

Does that help?

Regards,
Wendell

At 02:27 PM 9/28/01, you wrote:

> Thanks Matthew,
>
> I would have thought a .xsd or .dtd would be a KEY part of delivering a
> proposal for XSL.  One would think that that would unambiguously define the
> XSL formatting object language.  If anyone has any comments on that, I'd
> appreciated it.  Perhaps I'm missing something in the grand scheme of
> things.
>
> George.


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