A conventional response to opening bids of 1♥ or 1♠, showing game values or better and primary trump support, now popular with tournament players. A common system of opener’s rebids is as follows:
3♣/3♦/3 of unbid major singleton in suit bid.
3 of agreed major waiting, unsuitable for other actions.
3NT only four cards in the major.
4 of new suit pronounced two-suiter (good five-card suit on the side).
4 agreed suit minimum, no slam interest.
The two big advantages of the method are: You can find out a singleton in opener’s hand (like a splinter). By agreeing the trump suit at a low level and creating a game-forcing situation, the partners can exchange cue bids without having to go beyond game.
![](https://bernardmageebridge.com/wp-content/uploads/2021/11/image-151.png)
Without the information that West is short in spades, meaning that the hands fit very well, it would be hard for East to envisage a slam.