I-Data 5250 ALLY - Manual (Page 229)

APPENDIX C
PSEUDO TRANSPARENCY
Introduction
Most ASCII and EBCDIC printers have features that are not available on
IBM midrange printers. If the user’s application software is aware that the
destination of the data may be a non-IBM printer attached to a protocol
converter, the application can send printer commands that will activate the
printer’s advanced features.
Printer commands must be sent to the printer without being modified by
the System or the protocol converter. For this to occur, the commands
must be sent in a transparent packet. (Refer to the printer user’s manual for
a list of available printer commands.)
A transparent packet consists of a trigger followed by the data or command
that will be sent to the printer. The trigger alerts the protocol converter that
the data that follows it should be sent directly to the printer without
translation.
The 5250 ALLY will recognize the triggers for IBM transparency (35h),
ASCII transparency (03h) in IBM emulation mode, Xerox Metacode
transparency (35h) in IBM emulation mode, and Xerox transparency (36h)
in Xerox 275 twinax protocol converter emulation mode. The 5250 ALLY
will also support two forms of pseudo transparency.
i-data Pseudo Transparency
This form of pseudo transparency is valid only for twinax data streams
when the 5250 ALLY is in IBM emulation mode (!AGILE!03=00;).
The trigger used by i-data applications for pseudo transparency is
designated by the user within the application. The application sets the
trigger at the protocol converter by sending two ampersand characters
(&&), two question marks (??) and the designated transparency trigger.
For instance, to define the trigger as a percent sign (%), the application
would send the following command string:
&&??%