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Re: Attribute Uses

From: Henry S. Thompson <ht@cogsci.ed.ac.uk>
Date: 17 Jun 2002 11:26:39 +0100
To: John Verhaeg <jverhaeg@metamatrix.com>
Cc: "XML Schema Mailing List (E-mail)" <xmlschema-dev@w3.org>
Message-ID: <f5bk7oyxktc.fsf@cogsci.ed.ac.uk>

John Verhaeg <jverhaeg@metamatrix.com> writes:

> The "Attribute Use" described in section 3.2.2 of the Structures spec when a
> "ref" attribute is present seems to indicate that, if present, the
> default/fixed value must match the value specified in the declaration (the
> globally defined Attribute):

I think you're misreading the text below.

> "value constraint} If there is a default or a fixed [attribute]
> <http://www.w3.org/TR/xml-infoset/>, then a pair consisting of the ·actual
> value· (with respect to the {type definition} of the {attribute
> declaration}) of that [attribute] <http://www.w3.org/TR/xml-infoset/> and
> either default or fixed, as appropriate, otherwise ·absent·."

the 'as appropriate' means as determined by which [attribute] is
present.

> However, item 4 of Validation Rule: Attribute Locally Valid in section 3.2.4
> states:
> 
> "4 The item's ·actual value· must match the value of the {value constraint},
> if it is present and fixed. "
> 
> This seems to indicate that default values can be overridden in Attribute
> Uses.  XML Spy seems to allow the value to be overridden regardless of
> whether the value constraint is fixed or default.

That's correct, since defaults don't affect validation there's no
reason not to allow a change of default.

> Am I reading this incorrectly?  It seems as if there is both a documentation
> error in the spec and a problem with Spy.

So I think at best a clarification is needed in the spec. and I
disagree with Spy's allowing a 'fixed' value to be changed.

ht
-- 
  Henry S. Thompson, HCRC Language Technology Group, University of Edinburgh
          W3C Fellow 1999--2002, part-time member of W3C Team
     2 Buccleuch Place, Edinburgh EH8 9LW, SCOTLAND -- (44) 131 650-4440
	    Fax: (44) 131 650-4587, e-mail: ht@cogsci.ed.ac.uk
		     URL: http://www.ltg.ed.ac.uk/~ht/
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Received on Monday, 17 June 2002 06:26:43 GMT

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