In most helicopters, collective controls those two parameters, and cyclic controls speed and direction. However, in the 50s and 60s, the French broke away from this tradition. In their helicopters, they decided it would be better to fly at a fixed collective pitch, and fly the ac like a fixed wing. (And, at the same time, they decided to make their rotors go around in the opposite direction to everyone else!)
So their AFCS systems are optimised with different rules to 'most' helicopters, with the vertical channel being controlled by cyclic.
All helicopters, regardless of origin, with 3-axis autopilots fly using cyclic to control the vertical mode when it's engaged (and IAS when it's engaged). How else could they, with no collective coupling? That's why you can't have both IAS and a vertical mode engaged simultaneously on 3-axis machines.