> Also, the XSLT 2.0 spec states that "..the way in which the URI 
> reference is used to locate a stylesheet module is 
> implementation-defined." (section 3.10.1).  I presume this means that 
> setting the systemId on the Source object may work for Saxon 
> but is not guaranteed to work in general.

"Implementation-defined" can be read here as meaning "defined elsewhere, not
in this spec".

The JAXP specs and the URIResolver are entirely outside the scope of the
XSLT language definition.

Michael Kay