cue bidding controls during slam bidding
It can be seen from the other slam bidding conventions such as blackwood and Gerber that it is easily possible to find out how many aces or first round controls your partner holds when attempting to bid a slam contract but sometimes it is necessary to know exactly which suit(s) you have control of. To do this is not easy and it must be said the hands have to be "just right" in order to do it but cue bidding first round controls can give you the information you need. It works like this.
Let's say we have decided to try for a slam in diamonds. After some bidding on the hand on the left the auction has reached four diamonds when south realises there might be the possibility of a slam. S/he therefore bids five clubs, (lowest ranking ace), North, ignoring trumps, bids five spades and south can see all the aces are accounted for and carries on to bid a slam.
During cue bidding it is assumed that the ace of trumps is held. It is very important that cue bidding does NOT commence until both partners have decided which suit the contract is to be played in.
The lessons on this website are aimed at bridge beginners and it's unlikely that anyone in that position would be indulging in cue bidding because it's quite difficult to do. I have included it for the sake of completeness.