Other conventions

Here are a few useful conventions for describing strong hands when discovering slam possibilities.

Roman Blackwood

Roman Blackwood is an extension of Blackwood to convey additional information. Instead of the standard reply to the Blackwood 4NT asking for aces, it uses the so-called “Blue Team” responses to pinpoint which aces partner holds:

Response to 4NT Blackwood enquiry
5♣Shows 1 or 4 aces
5Shows 0 or 3 aces
5Shows 2 aces of the same rank
5♠Shows 2 aces of different rank and different colour (ie and ♣ or and ♠)
5NTShows 2 aces of the same colour

DOPI stands for Double-Zero-Pass-One convention. It is a convention used to deal with interference following the 4NT Blackwood call. Using the same bidding sequence as above, South has bid the 4NT Blackwood, asking partner for aces. An overcall from West of 5 interferes with this communication. DOPI is a convention that counters this interference:

DoubleI have 0 or 3 aces
PassI have 1 or 4 aces
5♠I have 2 aces

(PODI is similar, reversing the meaning of the double and pass calls, and this is a matter for partnership agreement).


Gerber is a bid of 4♣ in response to an opening bid of 1NT (or 2NT) and is asking for aces. North opens 1NT and South bids 4♣ indicating a powerful hand and an interest in going for a slam:

1NT4♣How many aces do you have?
4I have either none or 4 aces
4I have one ace
4♠I have two aces
4NTI have three aces
5♣How many kings do you have?
5I have either none or four kings
5I have one king
5♠I have two kings
5NTI have three kings

The replies from North are based on the Blackwood principal but at a lower level. South’s initial  4♣ response shows 13-20 points.

NorthSouthSouth's points

South can invoke Gerber, for example, on 13 points when holding an 8-card major; or on 21 points holding a 6-card minor. The convention may be extended to ask for kings by the 5♣ enquiry, as above. Some players agree for the King enquiry to be made with the next lowest available bid, as in this example:

1NTNorth has 12-14 points, a balanced hand and no rebiddable suit
4♣Opposite a 1NT opener South has 13-20 points and asks for aces
4North: I have one ace
At the next level South asks for Kings

South as responder
♠ 10
A Q J 10 8 6 4 2
♣ K 9 6

South has 14 points and a powerful 8-card suit. He bids 4♣ to ask North for aces. As a rough rule of thumb South can bid Gerber with 13 points if he has a good 8-card major; but needs 21 points with a good six-card minor to do so.

Gerber is always a jump bid in response to a no trump opener. Even a response of 5♣ to an opening bid of 3NT would be Gerber. Interference is dealt with in the same way as with Blackwood.

Handling confusion with conventions

Partners can mess up their communication if they confuse Blackwood and Gerber; Gerber and Swiss. And it is up to them to agree how they use any or all of these three conventions.

One suggestion is as follows:

4/4♣SwissResponse to 1/1♠ opening bidTrump support, indicating the number of aces held
4♣GerberResponse to 1NT/2NT opening bidAsking for aces
4NTBlackwoodResponse after one or more rounds of bidding where the trump suit has been agreedAsking for aces

This is not a perfect guide and experience will improve how these conventions are handled by the given partnership.  Of course, players are by no means required to use any of these conventions. It is strictly for partnership agreement. It is important, however, to know what the conventions mean as they will undoubtedly crop up when used by the opposition.

Just remember that Swiss is response to a suit opener; Gerber is a response to a no trump opener. Blackwood never faces an opening bid. It follows after a series of bidding when slam is definitely a prospect and the partnership wants to find the right fit.

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To continue reading go to: Overcalling with strength

By Nigel Benetton – based on the UK Acol Bridge Bidding System

Last updated: Thursday, 24th June 2021