Conventions in depth
Once a trump suit is agreed in a game-forcing auction, a new suit shows a control: an ace, king, singleton or void.
Roman Keycard Blackwood counts your aces, but it cannot tell you which suits they cover. A small slam can hold plenty of keycards and still go down at trick two because one side suit had no control. Control-showing cue-bids fill that gap: before anyone asks for aces, the partners tell each other where their controls actually are.
A control is a holding that stops the defence taking the first two tricks of a suit. An ace or a void is a first-round control; a king or a singleton is a second-round control.
In BidMaestro, a new-suit bid becomes a control bid once three things are true:
Typical launching points are a game-forcing raise such as Jacoby 2NT, an accepted limit raise with slam ambitions, the auction after a splinter, or any 2/1-style game force where a major has been set. What a control bid announces depends on whether you play Serious 3NT. With that convention on, a control bid instead of signing off in game is itself the slam try, and with no interest you bid game. With it off, after a two-over-one has agreed the major, any hand holding a control below game shows it, because partner is still unlimited and slam may belong to partner’s hand rather than yours. The replies then sort out the strength.
The app follows this scheme:
A control bid below four of the trump suit is cheap. If partner has nothing extra, the partnership still stops in game, and nothing has been lost by asking.
Once game has been reached, the next control bid is a different matter. It takes the auction to the five level, and there is no way back to four. The bid says three things at once: slam is still in view, this hand holds a control in the suit named, and it is content to play five of the trump suit if partner has nothing to add.
That last part decides when to make it. Bid past game only when five of the trump suit is safe opposite a minimum for partner’s bidding so far. Five never scores more than four, and it goes down on the hands where four would have made.
At this height a control bid shows a first-round control only, an ace or a void. Below game there is room to show a king or a singleton and still stop in four. Past game there is no cheaper bid left, and 4NT is behind you, so the bid has to mean the control partner cannot supply.
When you make one, BidMaestro shows its cheapest ace or void below five of the trump suit, and with neither to show it signs off in five. Once it has answered, it bids the small slam if every side suit that could be losing the first two tricks is covered, no more than one keycard can be missing and the two hands reach 27 points. Short of that it stops at five. A control bid higher than five of the trump suit commits the partnership to six.
| West | East |
|---|---|
| 1♠ | 2NT (Jacoby) |
| 4♠ | 5♣ |
| 5♥ | 6♠ |
West’s 4♠ shows a minimum opening with no shortage to report. East, too strong to pass that, cue-bids 5♣: a club control, slam still alive, and five spades safe whatever West holds. West shows the ace of hearts, the cheapest first-round control below five spades, and East bids the slam.
BidMaestro does not make this cue-bid itself. With a worthless side suit opposite a minimum it asks for keycards straight away. This choice was made by simulating a large number of hands and measuring the outcomes, which did not favour cue-bidding at the five level.
Skipping a suit is a message. A skipped suit, read correctly by both partners, is often the difference between a slam that makes and one that goes two down. In the second case the defenders cash the first two tricks in a suit nobody controlled.
| West | East |
|---|---|
| 1♥ | 2NT (Jacoby) |
| 3♥ | 4♣ |
| 4♦ | 4NT (RKCB) |
| 5♠ | 6♥ |
East’s 4♣ shows a club control and, by skipping 3♠, denies a spade control. West’s 4♦ shows a diamond control, and by carrying on rather than retreating to 4♥, West promises the spade control East denied. Every suit accounted for, East can ask for keycards with confidence.
Without control bids, East could count keycards with 4NT but would never learn whether two spade losers were waiting on the opening lead.
Once the picture is complete, one partner usually takes charge with 4NT Roman Keycard Blackwood. With a poor hand for slam, or a suit still without a control, either partner can stop by returning to the trump suit at the cheapest level; that is a sign-off, not another try.
Playing the Serious 3NT convention alongside, the two work together in a game-forcing major auction: 3NT shows real extra values, while cue-bidding past 3NT without it marks the courtesy tries. See Serious 3NT.
Below 3NT the same bids are usually probes for notrump rather than controls, so the method belongs chiefly to major-suit auctions.
← Back to all conventions