Well, now having reread the thread a few times....Purple was airside for the ramp, and on the pass in big letters you had either a D for your D licence, to drive the tugs and you needed a Restricted radio operators permit to talk to ground when you were moving aircraft around the apron from gate to gate. A standard drivers permit for the ramp was an avop. Airside Vehicle Operators Permit. Red was aircrew, Blue was building services, and I dunno the rest. Thas all I can remeber. And I guess, as I have read on the above link, fingerprints for the clearance. They never took prints from me before I was given a pass, I guess that is a post 9/11 thing. Good Luck.