CatIIIB No DH/RVR 75m.
CatIIIC No DH/RVR 0m.
As far as I am aware no Cat IIIc operators exist. As said above, the aircraft can do it (coz it does't know what the RVR is) effectively RVR doesn't matter to the aircraft! However its the pilots being able to operate the aircraft on the ground, that is the problem. I have never heard of one of these approaches being made. I can only imagine that it could be used to land in an RVR below 75m, in an emergency (fuel leak etc.) Just my thoughts....
Eff Oh.