[relax-ng] Predeclare xsd datatypes prefix?

[James Clark <jjc@jclark.com>]

I am wondering whether it would be a good idea to predeclare "xsd", i.e. 
assume a declaration of

  datatypes xsd = "http://www.w3.org/2001/XMLSchema-datatypes";

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

The advantage is convenience: it saves a user having to remember and type 
the XSD URI.  A small schema is very short and simple to write in the 
compact syntax, and having to type this declaration is a significant extra 
effort.  I find it hard to remember the namespace URI, and typically have 
to look it up, which I find a nuisance.

The disadvantage is that it is giving a priviliged position to XML Schema 
datatypes which RELAX NG itself is careful not to do. A counter argument to 
this is that the compact syntax is already doing an analagous thing by 
giving a special syntax to a:documentation.

I'm in two minds about this one.  What do other people think?

James