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On Wed, 2003-07-16 at 01:51, Bob Foster wrote:
> From: "Eric van der Vlist" <vdv@dyomedea.com>
> > > I am not sure this technical distinction helps the average schema
> writer.
> > > For example, rewriting an ambiguous schema so it is merely
> non-deterministic
> > > won't help XML Schema users. ;-}
> >
> > This chapter is in a book about Relax NG and its number one goal is to
> > help Relax NG users :-) ...
>
> Good point. Then you could probably omit that section on rewriting patterns
> so they are deterministic (or is it unambiguous?). RELAX NG users seldom
> need to do that. ;-}
That's right, however using deterministic patterns is a necessary
condition (although not sufficient) to get Relax NG schemas which
translate easily into W3C XML Schema (with the exception of choices of
values which translate into unions of simple types even when they are
ambiguous).
I should probably write some sort of table to summarise all this!
>
> > > The only case I can think of where the distinction makes any difference
> is
> > > in XML Schema union types, which are allowed to be non-deterministic but
> are
> > > not unambiguous because of the first-match rule.
> >
> > Or for using Relax NG tools (such as MSV) which can derive type
> > information out of unambiguous schemas whether deterministic or not
> > (more precisely, it will provide type information even if the schema is
> > ambiguous but I wouldn't always advise to rely on it).
>
> That's interesting. I assume you're talking about MSV when used as a SAX2
> filter. What does MSV do when it has multiple valid types, pick one?
Yes, it just picks one.
Thanks
Eric
--
Lisez-moi sur XMLfr.
http://xmlfr.org/index/person/eric+van+der+vlist/
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Eric van der Vlist http://xmlfr.org http://dyomedea.com
(W3C) XML Schema ISBN:0-596-00252-1 http://oreilly.com/catalog/xmlschema
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