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Re: XML Schema datatypes: NaN, lists of union types, [NEL], miscella neous editorial

From: Henry S. Thompson <ht@cogsci.ed.ac.uk>
Date: 05 Apr 2001 15:31:22 +0100
To: "Arnold, Curt" <Curt.Arnold@hyprotech.com>
Cc: "'www-xml-schema-comments@w3.org'" <www-xml-schema-comments@w3.org>, "'xml-dev@lists.xml.org'" <xml-dev@lists.xml.org>, "'malaika@us.ibm.com'" <malaika@us.ibm.com>
Message-ID: <f5bvgojto3p.fsf@cogsci.ed.ac.uk>
"Arnold, Curt" <Curt.Arnold@hyprotech.com> writes:

> 2. Barring lists of union types
> 
> Section 2.5.1.2 repeatedly defines list datatypes as lists of atomic
> datatypes (as opposed to union datatypes or list datatypes).
> Section 2.5.1.3 explicitly allows union datatypes to have members
> that are either atomic or list datatypes.  I assume that union
> datatypes are excluded from lists to prevent indirectly allowing
> lists of lists.
> 
> I would suggest that the value of allowing lists of union types is
> substantially greater than allowing unions that include list types.
> Unions of union types would also be significantly valuable.

This is a misunderstanding on your part -- the section referred to is
talking about the _value space_ of lists.  In the discussion of list
type definition, it is clear, e.g. at [1], that the 'itemType' of a
<list> may be union type definition.

ht

[1] http://www.w3.org/TR/xmlschema-2/#cos-list-of-atomic
-- 
  Henry S. Thompson, HCRC Language Technology Group, University of Edinburgh
          W3C Fellow 1999--2001, 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/
Received on Thursday, 5 April 2001 10:31:23 GMT

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