The ‘appx_print’ script can be replaced or modified if your spooling system provides additional functionality that the default script does not take advantage of. You may also wish to modify or replace the ‘appx_print’ script for debugging purposes. If you do modify ‘appx_print’, save the script under a new name and set the environment variable APPX_PRT_SCRIPT to the new script name. New or updated APPX releases will overlay the ‘appx_print’ script.
‘appx_print’ is expected to reside in the $APPXPATH directory. The name (but not the path) of ‘appx_print’ can be changed by setting the environment variable APPX_PRT_SCRIPT.
Underlines and Bold-Facing
APPX accomplishes both underlining and boldfacing using the same technique: overstriking using backspaces. In order to print an underlined character, APPX prints the desired character followed by a backspace character (hex 08), followed by an underline character. Boldfacing is accomplished by printing the desired character followed by a backspace followed by the desired character again. On printers that understand backspaces, this technique produces underlined and/or boldfacing. Some printers have configuration parameters that affect the interpretation of backspace characters.
If your printer does not treat backspaces as APPX expects, you can modify the ‘appx_print’ script to translate the backspace sequences into the form required by your printer.