The string datatype is an anti-datatype [was: The meaning of the "string" datatype?]

Rick, this is so cool:

> XML Schemas String datatype is perhaps 
> better thought of as an anti-datatype 
> rather than a datatype. What it does is 
> signify an absence of a value-space: it 
> is not asserted to be a number, not asserted 
> to be a date, not asserted to be a boolean.