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Re: List of union

From: Henry S. Thompson <ht@cogsci.ed.ac.uk>
Date: 15 Apr 2003 10:33:50 +0100
To: "Michael Marchegay" <mmarcheg@optonline.net>
Cc: <xmlschema-dev@w3.org>
Message-ID: <f5b1y0485q9.fsf@erasmus.inf.ed.ac.uk>

"Michael Marchegay" <mmarcheg@optonline.net> writes:

> Imagine that you have the following simple type definition:
> 
> <simpleType name="foo">
>   <list>
>     <simpleType>
>       <union>
>         <simpleType><list itemType="boolean"/><simpleType>
>       </union>
>     </simpleType>
>   <list>
> </simpleType>
> 
> The {base type definition} of foo is the Ěsimple ur-type definitionĚ;
> Derivation Valid (Restriction, Simple) is therefore not required;

Yes it is.  Sorry the name is confusing, we should probably have
changed it, but the prose at the beginning of 3.14.6 Constraints on
Simple Type Definition Schema Components reads:

  "All simple type definitions other than the simple ur-type
  definition and the built-in primitive datatype definitions (see
  Simple Type Definitions (3.14)) must satisfy both the following
  constraints."

Derivation Valid (Restriction, Simple) is the second constraint, and
thus applies to _all_ user-defined simple type definitions.

So your type definition is, as you hoped, ruled out.

ht
-- 
  Henry S. Thompson, HCRC Language Technology Group, University of Edinburgh
                      Half-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 Tuesday, 15 April 2003 05:33:52 GMT

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