> > Until now I was under the impression that the "instance of" operator
> > is usable only if the value has been type-annotated as result of
> > validation against a specific xml schema (as described on page 287 of
> > the XPath 2.0 book), (which may not be the case with a significant
> > part of all transformations written and used in the real world).
> >
> > Is my understanding of the applicability of the "instance of"
> > operator wrong ?
> 
> It's incomplete... For atomic values, you can simply do things like
> 
> 123 instance of xs:boolean  => false
> "123" instance of xs:string => true
> 
> Also for nodes, you can do
> 
> $node instance of comment()
> $node instance of element(para)
> 
> neither of which requires a schema.

Thank you. That's much better than I thought. 

Then I might  have a try at an f:type-of() function.


Cheers,
Dimitre Novatchev