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Re: Attribute Uses

From: Jeni Tennison <jeni@jenitennison.com>
Date: Fri, 7 Jun 2002 11:31:27 +0100
Message-ID: <1051625531040.20020607113127@jenitennison.com>
To: xmlschema-dev@w3.org, ht@cogsci.ed.ac.uk (Henry S. Thompson)
CC: John Verhaeg <jverhaeg@metamatrix.com>

Henry wrote:
> Misunderstanding: In the interesting case, i.e. where there is a local use
> with a ref to a global attr decl:
>   1) If the global has a fixed value, the local must have the same fixed
>   value, or no fixed or default at all.  In either case the fixed
>   value will be enforced.
>   2) When restrictions are checked, the same fallback is applied to
>   ensure that no change of fixed value occurs

Ah, right, thanks. I'd missed the fact that in Validation Rule:
Attribute Locally Valid
(http://www.w3.org/TR/xmlschema-1/#cvc-attribute), the attribute is
being checked against the {value constraint} of the attribute
*declaration*, and that there is a separate check against the {value
constraint} of the attribute *use* in Validation Rule: Attribute
Locally Valid (Use) (http://www.w3.org/TR/xmlschema-1/#cvc-au).

I'd also missed the Schema Component Constraint: Attribute Use Correct
(http://www.w3.org/TR/xmlschema-1/#au-props-correct) which states
that the attribute use must have the same value for its value
constraint it the attribute declaration's value constraint is fixed.



Jeni Tennison
Received on Friday, 7 June 2002 06:31:30 UTC

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