3270 or SLU 2 display devices

Because output to these devices establishes fields on the device using hardware capabilities, and field locations cannot be changed by the operator, special linkage restrictions exist.

Because formatted input can only occur from a screen formatted by output, the DPAGE and physical page definition used for formatting input is always the same as that used to format the previous output. Control block compilation by the MFS Language utility verifies that the MID referenced by the MOD refers to the same FMT name that the MOD references. During online processing, if the DIF corresponding to the previous DOF cannot be fetched, an error message is sent to the display.