Continuing in my series of "Conventions you don't need to know", I shall discuss one of the rarest openings in the game. In the absence of other agreement, you should assume that if partner opens 4NT then it is SPECIFIC ace-asking. If one merely wanted to know how many aces partner had, one could open 2 and later get out Blackwood. Thus a direct opener asks specifically which ones he has.
The following hand came up in the recent junior Camrose: A - KQJ9xx AKQJxx. With the ace of diamonds in partner's hands you would like to play 7, but without it, you'd settle for 6. Note that the ace of hearts is useless to you, so merely knowing how many aces partner has is no use.
The responses to a 4NT opener are:
5 = No ace
5// = the bid ace
5NT = any two aces
6 = Ace of clubs.
What happens if you have more that two aces? Don't worry - you won't have!
Thus, on our hand, if partner responds 5 or 5NT, bid a grand. If he bids 5 or 5, sign off in 6. If he bids anything else, give him a suspicious look!
WARNING: This bid should only be used when all you are interested in is aces!
Finally, for the more serious partnerships: you may feel you are all set to play this convention, but in real life the next hand overcalled 5! What now? I suggest that pass sounds like no aces, and double should be natural (note that any kings and queens you hold are likely to be useless to partner, but are probably defensive tricks), and cram in the other bids as you can, showing the diamond ace first, all the way to the club ace (but not bothering with two aces). Remember not to go higher than 6 (if partner could underwrite 6 opposite a wrong ace, so with it he should be able to bid higher than 6). Would you and your regular partner know this if it came up? No - I guess not!