Bridge by Steve Becker
There is obviously a big difference between a bidding sequence that goes 1 [S]-1 NT-3 [S], and one that goes 1 [S]-1 NT-4 [S]. The one-trump response indicates six to 10 points. Therefore, if opener rebids three spades, he is asking responder to continue bidding if he is in the upper half of the range for his notrump bid, and to pass if he is not. Expressed pointwise, responder is being urged to bid on with eight, nine or 10 points, and to pass with six or seven. The three-spade bid is thus an invitation — not a command —to responder to bid again. A four-spade bid is made by ...