The “Indication Rating (d)” is the algebraic difference in decibels (dB) between the Indication Level and the Reference Level with Correction for Attenuation as indicated in the following expressions:
Instruments with gain in dB:
Indication Rating => d = a - b - c
Where,
d = Indication Rating (dB)
a = Discontinuity Indication Level (dB)
b = Zero Reference Level (dB)
c = Attenuation factor (dB)