What does 'O' stand for?

[vintage ATCO]

Another example to decode is EDMM. E for northern Europe, D for Deutchland (Germany), M for Munchen (Munich) FIR, and M again for the Munich airport.

Forgive me as I haven't read the full article (but will later, I find the subject fascinating even though retired, sad, eh? ) but EDMM is the ACC at Munich, the airport is EDDM. In the days when I was addressing FPLs the ACC was also EDDM but was changed, as other German ACCs were, to differentiate them from the airports.

I have just noticed in the latest Doc7910 (ed 127 Mar 08) that it now contains the IATA three letter codes. How long has that been the case? Would have helped enormously, the airlines always spoke in IATA codes which I never got to grips with. Give me ICAO any time!