If the stylesheet is simply checking against a grammar, then you would
certainly be better off using a grammar-based validator. There are
essentially three candidates: DTDs, XML Schema, and RelaxNG. Which you
choose depends on all sorts of factors, personal, political and technical.

It might well be the case, of course, that your stylesheet is doing checks
that can't be described simply in a grammar.

Michael Kay
http://www.saxonica.com/ 

> -----Original Message-----
> From: Andrew Jeavons [mailto:apj@a...] 
> Sent: 04 March 2005 17:50
> To: xml-dev@l...
> Subject: [xml-dev] Schema, BNF and parsing
> 
> 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
> 
> 
> 
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