ATPL - QNH is the Q-code to indicate:

Question id 44 - IFR Communications - ATPL - Airline Transport Pilot license

The atmospheric pressure at aerodrome elevation (or at runway threshold)

The atmospheric pressure measured at the aerodrome reference point (ARP)

The altimeter sub-scale setting to obtain elevation when on the ground

The atmospheric pressure referred to the highest obstacle located on the surface of an aerodrome