[Zope] Oracle Stored Procedures and Transactions

I have a Script (Python) that does the following: stored_proc.AddUser stored_proc.AddTrees does some funky Python stuff zsqlmethod.insertPermissions I've had cases that my insertPermissions explode but the stored procedures have committed their data -- regardless of the transaction needing to be rolled back. In ZOPE, am I correct that everything inside a Request is in one Transaction (btw, how do you demarcate transactions?). Am I missing something? I am expecting that everything would be rolled back on a exception but it appears not. ~runyaga