Roman BlackwoodA variation of the convention, known as Roman Blackwood, was popularized by famous Italian Blue Team. In Roman Blackwood, the responses are even more ambiguous, but more space-conserving. The basic outline of responses is:
| 5♣ | – 0 or 3 aces |
| 5♦ | – 1 or 4 aces |
| 5♥ | – 2 aces |
In practice, the ambiguity is unlikely to occur, as a strength difference between hands with 0 or 1 and 3 or 4 aces is big enough that it can be established in previous rounds of bidding. In other words, a partner who has previously shown e.g. 12-15 range of high points is unlikely to hold 3 aces for his bid, etc.
Even Roman Blackwood convention has several variations, revolving around 5♥ and 5♠ responses. In all variants, they denote 2 aces. One variation is that 5♠ shows extra values, while 5♥ does not. In other variations, responses 5♥-5NT denote specific combinations of aces (same color, same rank, or "mixed").
If the querying partner ascertains that all aces are present, he can continue as follows:
In modern times, a system called Roman Key Card Blackwood (RKCB) has largely replaced the original sytem, at least among more advanced players. The king of trump is included as a control or a "key card"— in effect, as a "fifth ace"— and so more information is gained. The responses are basically the same as for Roman Blackwood, but with five "aces" in play, and aditionally queen of trumps:
| 5♣ | – 0 or 3 key cards |
| 5♦ | – 1 or 4 key cards |
| 5♥ | – 2 key cards without trump Queen |
| 5♠ | – 2 key cards with trump Queen |
As with Roman Blackwood, for the ambiguous answers in the minor suits the asking partner can almost always work out which it is by looking at the controls in his or her own hand and by analyzing the bidding. The response of five key cards does not exists, as it is simply forbidden for the partner lacking any key card to query Blackwood. The old bridge joke that applies here is, if your partner used RKCB (or regular Blackwood), and you have all four aces (or all five key cards, playing RKCB), then don't respond at all. Instead, rise slowly from your seat and leave the room quietly, because you are playing with a lunatic and your life may be in danger.
Even if partner gives a minor suit response to the RKCB 4NT inquiry, the inquiring partner may still determine if his side holds the queen of trumps. Bidding the next "meaningless" suit up from the 5-level response of the interrogated partner is a "queen ask" for the queen of trump. It is interesting to note that, in case when one player can ascertain that a 10-trump fit exists, the queen of trump is considered to be held even if it isn't, because two rounds of trumps will draw all the outstanding trumps in a very high percentage of the cases.
All the foregoing bidding is predicated on the assumption that a trump suit has been agreed upon. Without trump agreement, the last suit bid before the 4NT bid is considered to be the agreed trump suit for responding purposes. When No Trump was the last bid made, 4NT is considered to be a quantitative raise and invitational to a small slam. Therefore a bid of 4♣ (Gerber) is used in many partnerships to ask for aces in no trump sequences.
This guide is licensed under the GNU Free Documentation License. It uses material from the Wikipedia.
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