RE: Declaring more than one type for a parameter in x

> On the other side, I have raised the problem of some needed 
> missing super-types such as xs:numeric.
> 

I would also like to see union types accepted, e.g. a union of date, time,
and dateTime.

With elements, you may be able to handle it by defining substitution groups.
XML Schema 1.1 allows an element to be a member of several substitution
groups, giving you a complete lattice if you want it.

Michael Kay
http://www.saxonica.com/