I-Data 5250 ALLY - Manual (Page 165)

Page A-3 APPENDIX A — INTERFACING XEROX PRINTERS
The 5250 ALLY provides several methods that allow SCS and XES
documents to coexist in the same environment.
Coexistence
In order to eliminate the formatting conflicts that can arise when using
XES commands to control document formatting, the 5250 ALLY provides
two special modes of operation, one called PFS (Programmable Function
String) suppression mode, and the other called FF (Form Feed)
suppression mode. These two modes of operation can act independently or
in unison.
When the 5250 ALLY receives SCS commands from the host System, it
sends PFSs to the printer to simulate the behavior of the IBM printer it is
emulating. PFSs contain the XES commands used to control the printer.
When the 5250 ALLY is in one of its PFS suppression modes, it continues
to receive and interpret SCS commands from the host System; however, it
does not send the required PFSs to the printer. For the duration of PFS
suppression mode, the System effectively loses the ability to control
document formatting, allowing full control of the formatting via XES
commands. When PFS suppression is active, the only PFSs sent to the
printer are the INIT, CR, LF and FF PFSs.
When the 5250 ALLY is in one of its FF suppression modes, Form Feed
characters received from the host System are ignored. This allows the user
to fit a large number of XES commands on one physical page at the
printer, even though the System thinks it is printing multiple pages.
Delimiting XES Jobs
The 5250 ALLY provides two different methods of initiating and
terminating PFS and FF suppression based upon printable trigger
sequences. Auto PFS/FF suppression uses the natural format of an XES
mode “job” to automatically turn on PFS and/or FF suppression at the
beginning of an XES command data stream, and turn the suppression off at
the end of the XES command data stream.
For XES jobs that do not conform to conventions, and for compatibility
with existing applications and documents, the 5250 ALLY also supports
Logical Not (¬) commands that can be used to independently initiate and
terminate PFS and FF suppression modes.