Cruising Level
a) Flight Planned Cruising Level = the level the pilot is requesting to fly at. It is usually the optimum level for the aircraft taking into account all relevanty factors e.g. fuel consumption, wind velocity etc.
b) Assigned Cruising level = the level allocated by ATC to the flight.
Apart from low flying aircraft, cruising level will usually be a FLIGHT LEVEL
I don't think I agree here.........FPL is the level filed by the airline which may involve stepped climbs or descents to avoid flow regulations, RFL (requested) is the pilots prefered cruising level based on wind, weight etc often higher than the FPL if they can get it due to more efficient fuel burn.