The most top indication is a EPR indication. EPR stands for engine pressure ratio. Simplified it compares the pressure in front of the engine (more precise: in the intake forward of the LP Fan) and at the aft (one of the most aft stations of the turbine). If the engine is not operating on ground it should reed 1.0 because the pressure in front and at the aft of the engine should be equal. RR Engines are normally EPR controlled engines (only changing to N1 which is the opposite way to indicate "Thrust" if engine mode is degraded).