The simplest way to understand what a function code does is to try it and see what happens. Sometimes it is hard to figure out what has happened because nothing takes place. That is, the function code number may not be used.

I had a program at one time that built 16 Pronto pages with 16 buttons per page that had all possible (256) function codes for a specific device code of a specific protocol (e.g Sony 13 bit TV device)

The slow way is to associate the patterns (as many as you have) with a bunch of buttons and then to try them one at a time. Some will be obvious, some not.