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At 07:21 PM 5/8/2002 +1000, Rick Jelliffe wrote:
>From: "Jonathan Robie" <jonathan.robie@datadirect-technologies.com>
>
> > >The idea that a query system can optimise away, or generate errors on,
> > >queries like aaa/bbb if the schema specifies that aaa has no bbb children
> > >is also very worrying.
> >
> > Indeed.
> >
> > Whether or not that is an error is currently an open issue in XQuery. My
> > own view is that it should be neither a static nor a dynamic error, but
> > that it should evaluate to an empty sequence.
>
>Is that right? There is no way to say "Tell me what is in the document"
>if some schema has deemed something impossible. How the hell can
>anyone validate documents-in-progress (which may well be invalid)
>using that?
You are agreeing with my view, I believe.
Also, queries may operate on collections of documents, some of which do
have a given element, and some of which do not.
> > >How could one write schematron in Xpath2 if it
> > >needs to find exactly such cases and report errors? Xpath1 was designed
> > >to work on documents that specified a DTD but were invalid, not only
> > >well formed documents that did not specify a DTD. Is the same really
> > >true of Xpath2 wrt schema?
> >
> > This question has not been answered, it is an open issue. My own view is
> > that if the validation fails, XPath 2.0 and XQuery 1.0 should have
> > undefined behavior.
>
>So you are saying an XPath 2.0 can never be used to positively locate errors?
>What happened to the basic well-formedness versus valid distinction which
>allows manipulation and rectification of XML even when it is not valid
>using the same tools as when it is valid?
What I suggest would allow you to query the document as well formed, but
not to validate the PSVI of the document. I want to avoid querying a PSVI
that could only be constructed partially.
>Startled
>Rick Jellffe
Are you still started? If so, I'm still listening...
Jonathan
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