IDREFS

> On the other
> hand IDREFs are an XML 1.0 DTD feature that is purely to do with
> validation.

Also note that there are important DTDs that use IDREFS.  Notably XHTML 
uses it in the basic tables modules and DocBook also uses it.

I think it would a significantly loss from a marketing perspective not to 
able fully to validate XHTML or DocBook.

James