> I think When a user opens Invoice module and selects "NEW" I have to get a transaction number and use the number in all functions transactions, then if user preses "update" for the job I must commit all the changes to database that have the same transaction number. Or selects Cancel I have to do a RollBack operation. Think that all items at detail update fires 15 Functions.
>

Just a thought.

If more than one user uses the system, you'll most likely end up
with a GAP in invoice numbers. You can build logic to minimize
those gaps and mark the last ones left with VOID. Minimizing GAP
logic with a Invoice number based on department/salesperson/invoice
number used to work well for me. Getting an invoice number only at
time of posting from a IB6 procedure run in server might work
better.

Best Regards,
Hans