RE: Expressing relations between types

> I am thus wondering if there is a better way to define 
> "related" types like this.
> For example, is there a way to express the definition of 
> EntryPredicate by saying something like "this is the same 
> thing than an Entry, replacing dateTime by dateTimeRange, 
> unsingedInt by unsignedIntRange"?

Not within the XML Schema language.

Sometimes when your application contains higher-level structures or patterns
like this, it can be appropriate to describe the high-level structure in
your own notation and then generate the XML Schema definitions from this
(typically using XSLT to do the transformation).

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