Re: [xml-dev] What class of grammars is an XPath?

can say.
>
> ?? If the constraint is that  sum(//order/@value) > 826 must be true, 
> then it follows that //order/@value must have at least one member.

Fair enough. I was thinking the question was "what class of documents 
does this expression apply to", not "for what class of documents does 
this expression return true".

Michael Kay
Saxonica