OK, so if you don't want to use the XX just specify a local variable and never use it. So
F0 pp pp pp pp pp pp qq F7
Would be the incoming trigger that would recognize any 9 byte Sysex. The in rules, you just manipulate and/or output the qq portion for output.
So output for anote on might be
90 01 qq
I suspect though you might want to qualify some of the other incoming bytes with their actual values to illimatate 9 byte sysex that you do not want to process.
Steve Caldwell Bome Q and A Moderator and Independent Bome Consultant/Specialist bome@sniz.biz