Yes Chris it makes sense.
Throttle is directly connected to the PCU (prop control unit) and via a clever linkage to the FCU (fuel control unit). The electrical Fuel Trim Actuator is also connected via this linkage to the FCU.
This allows the RPM to be selected by the throttle and the power to be varied by the fuel trimmer. (+ or - 40 % I think)
I'd have to rummage in the loft to find a full description.
Typical power settings were as follows:-
Take off - 15000rpm max torque/ 100% trim
Climb - 14200rpm 760 degrees TGT set by trimmers (maybe 80% trim)
Cruise - 14200rpm 720 degrees TGT set by trimmers (maybe 60% trim)
These numbers are from memory and apply to the H.P. Herald.
Hope this helps.
P.S. CASC is "Combined Acceleration and Speed Control" as used on RR Spey not Dart.