>     Michael> In fact, in the Oct 2004 draft it's even simpler, but
>     Michael> this won't be available until Saxon 8.2:
> 
>     Michael> sum($seq/f(.))
> 
> What's the change that's made this possible?

The right-hand operand of "/" (sometimes referred to as "the last step in a
path expression") can now be any homogenous sequence, it is no longer
required to be a sequence of nodes. That is, it can be either a sequence of
nodes or a sequence of atomic values.

Michael Kay
http://www.saxonica.com/