My guess is they want to be able to do a modification to the radio by just by using a sequence of keypad entries.
Like some radios you would hold 9 1 7 and turn the radio on and it would put it into a test mode where you would have extra features.
My advice would be to check this site:
http://mods.dk
They seem to have the largest repository of radio mods online to my knowledge.
I don't own a 200xlt so no idea.