Just to add to what other have written-
if you're writing to anything based on this, you'll need some sort of
internal marker to tell if your data has been changed (i don't think
you're writing, but you should just be aware of this)
often i do one of two things:
a- have a 'checkout' table in the db, and have a block for x minutes
on similar operations (simple, but messy). only a var in the session
can get the checkout code from the db.
b- tie in a record version or some other logic to see if your data
set has been changed by someone else since you started your mutli-
page transaction
