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

[ht@cogsci.ed.ac.uk (Henry S. Thompson)]

"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
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