Some Q-codes are well known to pilots: QHN, QFE; some are studied in
ground class like QDR and QDM. Recently I heard say there also exists
one for "request to leave your frequency", ISTR it was QSR.

Which brings me to some questions:

-) where can I find a complete and authorative lsit of the Q-codes to be
used in aviation R/T?
-) who is the owner/maintainer of this list? They are international, so
it cannot be any national administration*. ICAO perhaps? But then I
understand some of these codes are also used by meteorologists and
sailors, too...?

TIA,
KA

* besides we have recently seen examples of the confusion that national
administrations can create through confusing or even contradictory
publications...