Custom parameter in Mission Planner?

Does anyone know if there is a parameter in ArduCopter software that is NOT used by ArduCopter, but is accessible from Mission Planner interface?
That parameter could be used in a custom subroutine added to ArduCopter by the user.

I have a need for such a parameter because I don’t want to having to dig into the AC code, change a number in my own subroutine that I added to AC and compile the program each and every time I need to make a small adjustment to one value in that subroutine. Doing it from Mission Planner would speed the process a thousand times.
Or… can I easily create such a parameter in Mission Planner?

Really appreciate your help.

yes you can create user defined parameters and only recompile the code once. That user defined parameter will automaticaly show up in mission planner without nedding to recompile mission planner.

Just read teh docs on how to add user parameters

Thanks a lot. You just made my day!