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Dare Obasanjo scripsit:
> On looking at the tutorial it seems this could be done if a RELAX NG
> implementation supported the W3C XML Schema Datatypes recommendation as
> a type library and implemented the facets as datatype parameters.
Just so: xsd:date params { minInclusive = "1990" maxInclusive = "2000" }
> However I don't see anything that implies that an implementation with
> such functionality exists or is forthcoming.
The Jing and Sun Multi-Schema validators both handle xSD datatypes,
so we can say that they are handled de facto if not de jure.
The schemas I write routinely assume them, and in fact the latest
version of the compact syntax quietly declares "xsd" for you.
> > but not nested constraints.
>
> Thought so.
Actually, I figured out how this could be done, although I can't
think of a clear use case for it. But abstractly, if you have
a type "foo" that is integers >= 1 and <= 1000, thus:
foo = xsd:integer params { minInclusive = "1" maxInclusive = "1000" }
then you can declare a subtype "bar" which has an inclusive upper bound of
100 thus:
bar = foo - xsd:integer params { minExclusive = 100 }
which is read "foo's except for integers with exclusive lower bound 100".
Because the specification is inside a negation, we need to change the
maxInclusive to a minExclusive.
> > How does one restrict complex types in WXS?
>
> A restriction of a complex type is a type that validates a subset of
> what the base type does.
I grasp that. Is it necessary to redeclare all the components of the
type, or only those which are changing? And how do we say that a
component is not found in the subtype at all (maxOccurs = "0", maybe?)
> > In the spec:
> >
> http://www.oasis-open.org/committees/relax-ng/spec-20011203.html#IDAG3YR
> >
> >Section 4.7, 3rd paragraph.
>
> Funny enough I found the language in the spec as hard to parse as when I
> first started reading the
> W3C XML Schema Structures recommendation less than a year ago.
I agree: the spec is quite difficult. It is the equivalent of
the (not yet cooked) formal model, not the schema.
--
John Cowan <jcowan@reutershealth.com> http://www.reutershealth.com
I amar prestar aen, han mathon ne nen, http://www.ccil.org/~cowan
han mathon ne chae, a han noston ne 'wilith. --Galadriel, _LOTR:FOTR_
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