"In late March, a programmer made a minor change in the program that was used to update the New York City Department of Social Services' master file. Because the revision was "trivial," the program was not tested. In the ensuing months, welfare recipients died, moved away, or lost their eligibility to receive further payments. Delete transactions were prepared in each case and processed as part of the normal master file update.

"The update program received both batch and online updates. Because of the program change, however, it no longer was able to handle both transactions. The "trivial" change caused the update program to ignore batchentered deletions to the master file, so closed cases remained open.

"During April, May, and June, the printers on the system kept spewing out checks. After the checks were burst and stuffed into envelopes, they went winging on their way to dead men, people who were long gone from the city, and those no longer entitled to receive payments. Finally, field workers started to report payments on closed cases. By this time, \(\$ 7,500,000\) had been disbursed to people who should have been deleted from the files.

"Now it is possible to go back and find which checks should not have been written. Getting the money back is a different question. Most of the checks are in the low three figures. It cost \(\$ 150\) to file legal papers to bring suit for recovery of the funds. Collecting the \(\$ 7,500,000\) might end up costing \(\$ 7,500,000 \ldots\). . . . Oh well, it wasn't real money! It came out of the taxpayers' pockets!

Required:
List the controls that would have prevented this fiasco from happening.