DLyons

There seem to be situations where one needs a mechanism to find a third round control in a specific suit before looking for Aces because the usual order may get you too high. For example, you open 1♥ holding ♠K 4 ♥K Q J 9 4 ♦A K 6 3 2 ♣A Partner bids 3♥ and you are missing two Aces and also need to know if partner has ♦xx or Q(*). Some partneships have 4♦ available as an asking bid and can then follow-up with a version of Blackwood. Is there anything known in general about the sort of situations in which control asking bids are the first priority? And about the most effective methods of making them?