WingFlaps schrieb:

Perhap we are at crossed purposes but an ARFOR does not refer to an
airfield -that's a METAR and not all fields issue them. So in this
case how can QNH give field elevation unless it's an ISA day?

Again: QNH gives *by definition* the field elevation. If an ARFOR gives
you a QNH, then it is related to one well defined spot on the surface.