First apologies if this is OT for this list or contains egregious 
assumptions and statements....I am not by any means a XML expert.

I have recently started working with a product which uses XML as the 
definition framework. We have a XML (QML we call it) which
describes how to ask questions. So QML has elements like "text", "sub 
question" and so on. We develop scripts which are validated for syntactic
validity and then passed to an execution engine. Of course the QML written 
has to conform to the schema defined. As far as I can currently work
out we use a 2666 line XLST script to check QML. QML is not a complex 
"language", it reminds me of IBM MVS JCL - 5 verbs and 200 qualifiers for 
the verbs.
2666 lines of anything to check this "language" seems extreme. I have 
written parsers using YACC in the past and it seems to me for numerous 
reasons using
some sort of BNF/EBNF defined grammer and Bison/YACC type tools will be 
VASTLY more efficient and flexible. What I would like to ask is are there any
tools anywhere to convert a schema to BNF/EBNF ?

thanks
andrew

Andrew Jeavons