> I have seen expressions like :
> translate($xxx, 'ABCDE','x');
> which is to say, replace ABCDE with x .. this also works fine
> is this not valid?

I have seen expressions like this too. It's up there in the list of common
XPath coding mistakes. It's valid, but it does something completely different
from what the user probably intended. One of those mistakes you make if you
guess what a function does from its name, without actually reading the spec.

Michael Kay
Saxonica