A British system of bidding which incorporates some of the features of American Standard style.

1. Strong no-trump opening bids, with Gladiator responses. (Responses of two diamonds, hearts, or spades are constructive and non-forcing.)
2. Jump raises and two no trump responses are forcing except in competition.
3. Suit opening bids are unprepared. One spade would be bid with S-Akxx, H-Axx, D-xx, CQxxx. After a response at the level of two (10 points or more), the opener can rebid two no trump with a minimum hand.
4. A conventional TWO CLUBS, with ace showing responses. A subsequent four no trump bid asks for kings on the Blackwood principle.
5. Cue bids to show controls are used extensively, and in some situations are compulsory.
6. Acol Two-bids: a suit response at the two level may consist of no more than a fair five card suit.
7. Opening three bids in a minor suit invite three no trump; either the suit is solid, or it is nearly solid and there is an outside entry.

The initials CAB stand for two Clubs, Ace showing, and Blackwood, the chief contributions to the development of the system.