substitute to assignment statements?!

["Palaniappan, Krishnasamy" <Pa...@diebold.com>]

Hi,
I have a situation where I need to use something like a boolean variable. What is the substitute for that in FOP? As I understand, all variables are constants.
Basically, I have a loop and each time I get into the loop, I need to check for a variable as to whether it is true or false and act accordingly. If it is true, I do something and need to then set it to false.
How do i handle something like this in the XSL world!?
Thanks for your inputs,
Regards,
Krish
p.s.: Please cc to palanik@diebold.com