RE: Cutting the Patrician datatype knot

Date: 11/30/01

> -----Original Message-----
> From: ext Ashok Malhotra []
> Sent: 29 November, 2001 08:25
> To: Stickler Patrick (NRC/Tampere);
> Cc:;
> Subject: RE: Cutting the Patrician datatype knot
> > In the above union "data type", the literal "7" maps to
> > two members of the value space. Therefore, it is not a
> > valid data type.
> If you define a union type then such anomalies can arise.
> XML Schema specifies how to resolve them.  If a literal can be 
> interpreted as a valid literal for more than one of the datatypes
> included in a union, it is assumed to have the datatype of the first
> datatype specified in the union for which it is a legal literal.
> You may not think this is an elegant solution but it solves the 
> problem. 

But doesn't that then preclude the use of (hide) a subset
of the value space? I.e. whatever the intersection is between
the two (or more) value spaces, only the members of that
intersection belonging to the first data type are "accessible".

Well, if that's how the union data type is defined to work, then
it's not technically a problem -- i.e. there really is no actual
ambiguity in the mapping -- but it would still IMO be a very 
odd data type ;-)



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