re: [relax-ng] Predeclare xsd datatypes prefix?

Message text written by James Clark
>
  datatypes xsd = "http://www.w3.org/2001/XMLSchema-datatypes"

A user would be able to override this if they wanted.
<<<<<

James,

Why not declare it as an abstract URL?  Why does it have to be
physical??  This always struck me as totally silly anyway!

Therefore :

 datatypes xsd="%default.schema.types%"

where the implementor can define %default.schema.types% for 
a particular scenario.

I may want to point this at :

 define 

     default.schema.types = "http://relax.xmlglobal.com/schema-datatypes"

for instance.

DW.