There was a similar catastrophe at Jewel osco stores many years ago. Nightly, items added to the store pos were merged back with the main item file at each store location. The format of the merged data was exactly the same as loading a new file, except the first statement would be /EDIT instead of /LOAD.

One of the programmers decided to eliminate some code by combining the two functions, with a switch to control whether /LOAD or /EDIT was used for the first statement.

There was a bug in the program, and the edits were sent down as loads.

A guy I knew, Barry, was the main operator that night. He started getting calls from the stores after around 10 of them had been reloaded with 5 or 6 items.

Barry said it was the first time he got to meet the president of the company that day.

This was back when phone lines were used to transmit data, and it took several hours just to transmit an item file. So, the store locations were out of business until the item file could be restored.