|Location||Toolkit II, THOR XVI|
The command PROG_USE and dependent commands behave in the same way as DATA_USE with a few differences.
The program device set with PROG_USE is used by the EX (EXEC), EW (EXEC_W) and (exceptionally SEXEC) commands as the default device. Whereas some commands which use the data device (eg. MERGE, LOAD) check the program device if they do not find a given file on the data device, the above commands which use the program device will not look at the data device should they fail on the program device.
The default devices cannot exceed 32 characters (plus a final underscore) - any attempt to assign a longer string will result in the error ‘Bad Parameter’ (error -15).