Definetely
Turbofan Power Ratio.
From the RR Trent training notes,
"TPR actual is derived from the P20, P30, T20 and EGT parameters."
Calculated in the following manner;
.
. P3.0 x √ EGT
_____________ =
TPR
.
P2.0 x √T2.0 .
.
P2.0 = Engine Inlet airpressure
P3.0 = HP Compressor Discharge Pressure
T2.0 = Engine Inlet Temperature
EGT = Exhaust Gas Temperature
.
.