The aircraft I fly is cat 3B we have a DH of 50ft and we require an RVR of 150m.
Some of our company aircfaft are cat3A, they need 200m RVR but still have a DH of 50ft.
On the other hand the 777 is cat 3C and they (I think) only need an RVR of 75m and have a zero DH, and even with a 50 ft DH and a heavy aeroplane the wheels have been known to touch the ground, they definately do when we practice engine failures in the simulator, and have to go around on three engines.
I think it is usually the aircraft and the company that determine the minima not the airport, so I am not to sure exactly what you are asking.
As I understand things if an airfield is cat 3, and we as an operator have cat 3 minima for that airfield then we are permitted to operate to our cat3(B) mimima.