Look for the following section in appx_print.  Remove or comment it out.
If you are doing client-side printing, appx_print will be in the client
install directory.  Otherwise, look for it in the $APPXPATH directory on
the server.

This is only for non-windows operating systems. Windows client and server
systems do not use mpage or appx_print.

#
# default format if one wasn't specified
#
if [ "$FORMAT" = "" ]
then
 FORMAT="MPAGE"
fi