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> Hi,
>
> Does the following allow 'abc' as a valid value?
>
> <xs:simpleType name="MyDouble">
> <xs:restriction base="xs:double">
> <xs:pattern value="[^N].*"/>
> </xs:restriction>
> </xs:simpleType>
>
> We had been working under the belief that, via restriction - patterns
> from both the new datatype and the original one are 'And'ed together.
> i.e - the above datatype would only allow values valid for a double -
> with the exception of NaN.
>
> However, we've read somewhere today that whenever a pattern facet is
> evaluated - it is evaluated against a string. Though XMLSpy and Xerces
The 'XML Schema Part 2: Datatypes' says
NOTE: It is a consequence of the schema representation constraint Multiple
patterns (?4.3.4.3) and of the rules for žrestrictionž that žpatternž
facets specified on the same step in a type derivation are ORed together, while
žpatternž facets specified on different steps of a type derivation are ANDed
together.
'pattern' is a constraining facet, and a type defined by applying a constraining
facet to a primitive type is a derived type.
Therefore, I would think that 'pattern' defines a subset of the lexical space of
the type it is applied to.
David Tolpin
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