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Re: patterns and restrictions

• To: xml-dev@l...
• Subject: Re: patterns and restrictions
• From: David Tolpin <dvd@d...>
• Date: Wed, 17 Dec 2003 19:42:31 +0400 (AMT)
• In-reply-to: <3FE07653.4050000@m...>

[ Charset ISO-8859-1 unsupported, converting... ]
> 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 ?restriction? that ?pattern?
facets specified on the same step in a type derivation are ORed together, while
?pattern? 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

• Follow-Ups:
  • RE: patterns and restrictions
    • From: "Alessandro Triglia" <sandro@m...>
  • Re: patterns and restrictions
    • From: Max Chappell <max@m...>

• References:
  • patterns and restrictions
    • From: Max Chappell <max@m...>

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