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

[Michael Kay <mike@saxonica.com>]

>
> Anyway, it is an interesting question. I think the same question could 
> be asked, rephrased, as "what is the smallest class of formal grammars 
> that every Xpath (evaluating to boolean) belongs to?"
>

I don't understand the question. There's no grammar that precisely 
describes the set of documents for which the expression

sum(//order/@value) > 826

returns true. It's not a grammatical constraint.

Michael Kay
Saxonica