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Re: Cross-schema restrictions

From: Jeni Tennison <jeni@jenitennison.com>
Date: Thu, 28 Nov 2002 16:20:01 +0000
Message-ID: <12642436570.20021128162001@jenitennison.com>
To: xmlschema-dev@w3.org, Robin Berjon <robin.berjon@expway.fr>
CC: CÚdric Thienot <cedric.thienot@expway.fr>

Hi Robin,

> My question is: is that even a valid restriction? In schema B, eltA
> would appear to me to be in effect B:eltA, and thus not valid per
> ctA. I couldn't find text in the spec to make me balance either way
> (but then I could have missed it), though I would prefer that
> restriction to be impossible.

It's not a valid restriction, for the reason you cite -- the
definition of A:ctA has a content model that contains a reference to
A:eltA. In schema B, you define the content model of B:ctB to include
an element called B:eltA. This isn't valid under Schema Component
Constraint: Particle Valid (Restriction) [1]. Specifically B:eltA is
not a valid restriction of A:eltA under clause 1 of Schema Component
Constraint: Particle Restriction OK (Elt:Elt -- NameAndTypeOK) because
the elements' target namespaces are not the same.

I'd usually get around this using substitution groups, but that
wouldn't work in your example because you can't use substitution
groups with attributes, only with elements.



[1] http://www.w3.org/TR/xmlschema-1/#cos-particle-restrict
[2] http://www.w3.org/TR/xmlschema-1/#rcase-NameAndTypeOK

Jeni Tennison
Received on Thursday, 28 November 2002 11:20:03 UTC

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