The 1♦ response usually shows 4+ cards and 6+ points. Such 1♣-1♦ is the most constructive auction. Because it is too constructive and shows no major, modern bridge players make many reasonable adjustments to the 1♦ response.
Wbridge5 is no exception. We adjust 1♦ according to responder's strength.
- 6~11 points
- With a biddable major, skip diamonds unless 6+ cards or at least AJxxx or KQJxx.
- 17+ points
- Bid strategic 1♦ with some hands indescribable by strong jump shifts.
In Wbridge5, an 1NT rebid always denies biddable major because 1NT is difficult to make with average strength. Moreover, no singleton is allowed in the 1NT rebid. Therefore, responder can buy 2♠/♥ with only 5 cards.
In contrast, the 2NT rebid shows a balanced hand or 2=2=4=5. A 4-card major is allowed in a balanced hand. So descriptive can 2NT be because there is almost always 23+ HCP in our partnership. Since 2NT collects all balanced hands, the strong jump shifts 2♠/♥ contain 5+ clubs unless 2♥ with 4-4-4-1.
Beware that all these rebids are nonforcing. Responder can always pass when a game is unlikely.
The rebidding strategy is the same for all suit responses. The strategy is described in the page of major rebids for frequency and a more general overview.
- Responder passed, 11~12 HCP, exactly 3 diamonds.
- 1♥, 1♠
- 13~18 points, 4+ cards.
- 12~14 HCP, balanced or 5-4-2-2, no biddable major.
- 13~18 points, 5+ cards, unbalanced.
- 4+ cards, some singleton or void.
- 2♥, 2♠
- 19+ points, 4+ cards, unbalanced or 5-4-2-2.
- 18~19 HCP, balanced or 2=2=4=5.
- 19+ points, 6+ cards.
- 18~19 HCP, 6-3-2-2.
A hand with 20 HCP and 6-3-2-2 is strong enough to open 2♣. Therefore, the 3NT still shows 18~19 HCP.
The 2♦ rebid is surprisingly unlimited. This unusual treatment produces good results in practice. Tactics are described in a dedicated subsection [not yet written].