In the case, as an example, that the Ace-asking partner receives the response of 5 Hearts, then the Ace-asking partner, holding the Ace of Hearts, for example, expects the responder to hold the Ace of Clubs and a second, unspecified Ace.
It is this ambiguity or flaw that the British-style Roman Blackwood variation addresses. In order to overcome this inconsistency, this variation added an extra response to clarify the response. The responses are shown below. Source: oeb
5  : |
Shows 0 to 3 Aces. |
5  : |
Shows 1 or 4 Aces. |
5  : |
Shows 2 Aces of the same color, / or / . |
| 5 : |
Shows 2 Aces of the same rank, / or /. |
| 5 NT: |
Shows 2 Aces of dissimilar or unlike color and rank, or / or /. |
Alternate Approachs for King Inquiry
In the case that the first response of the responder to an Ace-asking 4 No Trump is 5 No Trump, then the partnership really has no normal way to ask for Kings. However, the partnership may use any other, additional conventional method to ask for Kings, which means the employment of a second conventional method singly to ask for Kings.
Since it has proven to be more effective in judging the possibility of a grand slam to know the the location and/or identity of a specific King, some partnerships have agreed to employ a different approach if the normal response would be 5 No Trump. The partnership agrees simply to employ the bid of 5 Hearts to show two Aces and no additional values, and employ the bid of 5 Spades to show additional values and strength.
Since the Ace-asking partner is able to infer from the Major suit responses that the responder should have bid 5 No Trump, then the Ace-asking partner has the communicated information that the two Aces are of dissimilar color and rank plus the additional information about the held values.
The Ace-asking partner is able to infer the correct conventional bid by receiving contradictory (or incorrect) information from the responder, and will bid accordingly. It must also be noted that the partnership may benefit from agreeing to employ two different conventional methods, one for the Ace-ask and one for the King-ask.
If you wish to include this feature, or any other feature, of the game of bridge in your partnership agreement, then please make certain that the concept is understood by both partners. Be aware whether or not the feature is alertable or not and whether an announcement should or must be made. Check with the governing body and/or the bridge district and/or the bridge unit prior to the game to establish the guidelines applied. Please include the particular feature on your convention card in order that your opponents are also aware of this feature during the bidding process, since this information must be made known to them according to the Laws of Duplicate Contract Bridge. We do not always include the procedure regarding Alerts and/or Announcements, since these regulations are changed and revised during time by the governing body. It is our intention only to present the information as concisely and as accurately as possible.