Many computer installations used cards with the opposite corner cut (sometimes no corner cut) as "job separators", so that an operator could stack several job decks in the card reader at the same time and be able to quickly separate the decks manually when they removed them from the stacker. These cards (e.g., a JCL "JOB" card to start a new job) were often pre-punched in large quantities in advance. This was especially useful when the main computer did not read the cards directly, but instead read their images from magnetic tape that was prepared offline by smaller computers such as the IBM 1401. After reading the cards in, the computer operator would return the card deck – typically to one of a set of alphabetically labelled cubby holes, based on the programmer's last initial. Because programs were run in batch-mode processing it might be a considerable time before any hardcopy printed or punched output was produced, and put into these same cubby holes – however, on a lightly-used system, it was possible to make alterations and rerun a program in less than an hour.