Marking the start of a job was a punched card that started with codice_1. Any card that started with codice_2 was a command to the Supervisor and could not be used as user program or data. Other commands included codice_3 to execute the Disk Utility Program (to delete files or add the file in the temporary area to the file collection) and codice_4 to execute a named program from disk. If a user program tried to read a command card, the standard card reader routine would signal end-of-input to the program and save that card's content for the Supervisor.