W3C home > Mailing lists > Public > xmlschema-dev@w3.org > June 2002

RE: Clarification on enumerations

From: Michael Leditschke <mike@ammd.com.au>
Date: Wed, 19 Jun 2002 23:42:41 +1000
To: "Jeni Tennison" <jeni@jenitennison.com>
Cc: <xmlschema-dev@w3.org>

<snip />
> If you want to restrict the lexical representation, use a pattern as
> well (or instead, but as well is better because it enables other
> applications to get access to the enumerated values without having to
> have a fairly sophisticated regular expression parser):
> <xs:simpleType name="AFewNumbers">
>   <xs:restriction base="xs:decimal">
>     <xs:enumeration value="1.2" />
>     <xs:enumeration value="5.5" />
>     <xs:pattern value="1\.2" />
>     <xs:pattern value="5\.5" />
>   </xs:restriction>
> </xs:simpleType>

Hi Jeni. Thanks for the clarification.

Its interesting to me that you added pattern 
facts and framed them in terms of restricting the *lexical* 
representation. I have thought of pattern as operating in 
the lexical space as well.

However the REC seems slightly at odds with this. The definition
of the pattern facet suggests it operates primarily in the lexical 
space, and thus affects the value space as a secondary effect.

However the definition of a facets suggests it must operate
primarily on the value space

"A facet is a single defining aspect of a .value space.." 

I guess it comes down to interpretation of language - a problem 
with all specs - but to me a pattern is "a single defining aspect"
of the lexical space, not the value space. In which case, shouldn't
the definition of a facet be a bit broader (as it is by implication
in the definition of a datatype)?

Received on Wednesday, 19 June 2002 09:43:13 UTC

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