Hi Michael,
I don't think there's likely to be any significant difference between using
a single-valued key, as shown here, and using a global variable. Using a
global variable seems much more intuitive.
But here I'm guessing.
I agree, a global variable is about as good as a single-key index (not single-valued!). Though, my
impression on some XSLT 1 implementations was that the keying mechanism is more optimized to
traverse the document than the evaluation of //. And accessing a key instead of a variable might
make a difference as well.
But I agree: there is only one way to find out: measuring it. :-)
Grtz,
Geert