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Re: Can XML Schemas Support Document Systems (WAS RE: ZDNetSchemaarticle

• From: Eric van der Vlist <vdv@d...>
• To: xml-dev <xml-dev@l...>
• Date: Fri, 27 Apr 2001 09:20:13 +0200

"C. M. Sperberg-McQueen" wrote:
> 
> I invite people to show that the requirement for determinism
> (i.e. for LL(1) grammars) can be dropped without hurting anybody,
> because then maybe we can get consensus on dropping it in some
> future version.

Yes, that's why it's interesting to follow initiatives from informal
groups without much legacy to protect.

I hope we can define ways to integrate these initiatives in the overall
picture, technically first (though a modular structure that lets people
choose the schema language they wish to use) and later on by eventually
integrating some of their features in standards.

I also think that there might be other ways to to introduce determinism
if required by learning from the experience of XSLT.

A schema validation is nothing but a transformation that transforms
instance documents into a validation report and/or a PSVI.

It should then be possible to solve un-derterminism (i.e. to make sure
the validation report and/or PSVI are producing a deterministic result)
by defining overrideable priorities ala XSLT.

> But interpreting it as an innovation imposed on the document
> community by dataheads is just wrong:  if the non-determinism
> rule is bad for document processing, it's a self-inflicted wound.

Yes, I get your point!

The fact I have no SGML background and have taken for granted that I
could work without DTD is probably a reason why I those constrains do
not look "natural" for me.

What I meant is that the consequences of non determinism are more
important for data processing (you don't want to take the risk of an
error of interpretation of a field in an invoice) than for documents.
 
> >For example, you can't define a simple and flexible vocabulary where a
> >document would have a title, an optional description and any number of
> >paragraphs without imposing a relative order to the different elements.
> 
> Huh?  It's complicated, but it's doable.
> 
>    (p*, ((title, p*, desc?) | (desc, p*, title)), p*)

I should have added more elements ;) ...

Thanks for your answer.

Eric
 
> 
> -Michael Sperberg-McQueen
>   speaking only for himself
> 
-- 
See you in Hong Kong for www10:
                     http://www.www10.org/program/w10-half-tut.shtml#ta5
------------------------------------------------------------------------
Eric van der Vlist       Dyomedea                    http://dyomedea.com
http://xmlfr.org         http://4xt.org           http://examplotron.org
------------------------------------------------------------------------

• References:
  • Can XML Schemas Support Document Systems (WAS RE: ZDNet Schema article,and hiding complexity within user-friendly products)
    • From: "Bullard, Claude L (Len)" <clbullar@i...>
  • Re: Can XML Schemas Support Document Systems (WAS RE: ZDNet Schemaarticle,and hiding complexity within user-friendly products)
    • From: "C. M. Sperberg-McQueen" <cmsmcq@a...>

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