@ Cmdr Jennifer: You said what I meant,but your explanation is indeed a lot better than mine.
@ forzaniller: For example, in the German turn. Suppose the Germans have rockets, and the AA-guns are in W-Eur, Ger and S-Eur. All three can hit the UK-IC, but only one of those three may hit the UK-IC. However, the W-Eur AA-gun may hit UK-IC and the S-Eur AA-gun may hit Caucasus.
Now suppose Germany has 2 AA-guns in S-Eur and has rockets. Only one of those two AA-guns may fire this turn, either at UK-IC or Caucasus-IC. But the second AA-gun may not fire this turn, as the other one in S-Eur already has.
I think this is correct, and otherwise someone will correct me(I’m looking at you Cmdr Jennifer :-D)