Roman Blackwood

A variation in responding to Blackwood that will sometimes determine which ace is missing (when the partnership holds three aces.) The responses are:

5C shows 0 or 3 aces;
5D shows 1 or 4 aces;
5H shows 2 aces of the same color or adjacent in rank;
5S shows two other aces than for 5H.

See Roman Key-Card Blackwood for a more popular variant.