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In W3C XML Schema, datatypes are to a certain extent an abstraction --
the combination of a lexical space, a value space and a mapping
between them -- that is meant to be usable via a range of concrete
mechanisms.

W3C XML Schema itself has such a concrete mechanism:  the Simple
Type Definition component.  This in turn may appear and function in
three contexts:

 1) As the {type definition} of an Attribute Declaration;
 2) As the {type definition} of an Element Declaration;
 3) As the {content type} of a Complex Type Definition (which itself
    will typically be the {type definition} of an Element
    Declaration).

The validation semantics of (1) -- (3) are all defined in terms of
properties of the corresponding datatype.

Hope this helps,

ht
=2D -- 
 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@i...
                   URL: http://www.ltg.ed.ac.uk/~ht/
[mail really from me _always_ has this .sig -- mail without it is forged sp=
am]
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From david.landwehr@s... Tue May 09 09:45:27 2006
Received: from magg