Re: Keeping a running total?

Hmm... I was thinking there may be some kind of hack involving
sum(beginning->current factory).

You're out of luck with for-each, because conceptually at least it processes
all the factories in parallel. So you can't accumulate data as you go.
Instead for this kind of problem you need recursion: to a process a list of
factories, process the first factory, then process the rest of the factories
by a recursive call, passing any necessary data (such as your "running
total") as a parameter.

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