of room to find a safe landing spot, when partner's hand is too weak to go on to game—which happens quite often in actual play. The second major advantage is that it immediately tells the opening bidder the combined high card strength of the two hands to within one HCP, and thus the most probable optimal level to which to bid (with the caveat that one sometimes can go a level higher with a good trump fit). The first drawback is that the weaker hand occasionally will end up declaring a contract with a trump fit in the major suit of the response. (Note that a transfer following opener's rebid of 2NT over a response of either 2 or 2 may be to the suit of the response. Such transfers cannot achieve the objective of making the strong hand the declarer, but they still help to find such a trump fit.) The second drawback is that it uses up some bidding space if the responder has an unusually strong hand. Nonetheless, opener's minimum of 22 HCP leaves a maximum of 18 HCP distributed among the other three hands. It's quite rare for responder to hold more than half of them. Indeed, this convention has gained popularity both for its simplicity (comparable to standard Blackwood) and for the infrequent occurrence and relatively minor consequences of its drawbacks. The origin of this convention is uncertain. Some players have attributed it to Oswald Jacoby, of Jacoby Transfer and Jacoby 2NT fame, while others refer to it as "Castlebury" (or "Castleberry"?), but the present author is not aware of any source that would verify either attribution. Control-showing responses Some players prefer to show their controls (high cards) rather than suits in the response to 2 opening bid. This has an advantage in cases when the opener has a strong one- or two-suiter (i.e. has an interest in cover cards rather than finding the suit fit), but can take up bidding space and miss a suit fit when the opener is balanced or semi-balanced. In standard "controls," an ace counts as two controls and a king counts as one control. The theoretical advantage of this system is that aces and kings may be more significant for finding a potential slam than other honor cards, but it also may miss a slam opportunity if the responder has a lot of inferior honor cards. There are several