[xsl] Any way to specify diagnostic message for missing stylesheet parameter?

["David Sewell dsewell@xxxxxxxxxxxx" <xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx>]

Given a stylesheet parameter <xsl:param name="somevar" required="yes"/>, 
failing to supply a parameter value at run-time results in a boilerplate error 
message such as "XTDE0050: No value supplied for required parameter somevar".

It would be helpful to be able to supply a custom error message such 
as "required: somevar=[true|false|unknown]" to save the user the time it takes 
to look through the code to figure out what parameter is expected. There's no 
way to do this in the XSLT spec through 3.0, correct? and no common extensions 
for doing it?

If not, would that be a useful feature for others, or are there reasons not to 
implement something like that as an extension or enhancement?

David

--
David Sewell, Editorial and Technical Manager
ROTUNDA, The University of Virginia Press
PO Box 400314, Charlottesville, VA 22904-4314 USA
Email: dsewell@xxxxxxxxxxxx   Tel: +1 434 924 9973
Web: http://rotunda.upress.virginia.edu/