Re: [Zope] How to prevent the user from going "Back" to a page???

Use a session tracking product, that'll give you a session id and ocne the session is complete, you can return an error if that session id is presented again.

I'd probably handle this instead by computing an identifier for the transaction and including it as a hidden form field on the submission page. Keeping one day's worth of transaction ids somewhere to check against in the form action would probably suffice.