System produces a check report. System does not know if you have printed the check report on the check stock or not. After formatting program is run (check report is produced) you can either confirm that all was printed well or you can terminate your pay run. You will only terminate your pay run if you have not printed the check report on the check stock. Otherwise your check numbers on check stock will be out of sync with Oracle.

Once you terminate your pay run, everything goes back to as if it was never run. There is no accounting impact and no check numbers used.

You create payment process, the status is New.
While system is building payments the status changes to Assembling Payments.
Then the format program is run the status changes for Formatting.
Next step is to confirm or to terminate.
You can click on Take Action button available for your payment process and then click on Terminate on the next screen.
Hope that helps.