PT6 has:
Reverse: 'nuff said
Ground range: For taxiing where the engine stays at (I think) circa 75% N1 and the prop moves within the beta range to control taxiing thrust; The lowest of which is ground idle.
Flight Range: N1 moves to 100% N1 and the blade angle into the Alpha range and that adjusts the blade angle to control thrust. The lowest of which is Flight Idle. When the power is adjusted then the blades change angle to maintain a set RPM.
Ok?