Two-way checkback is a convention. This convention is alertable.
Two-way checkback is a convention to find a major suit fit. It is similar to 2♣ Stayman after 1NT opening, but two-way checkback is applied by the responder after a 1NT or 2NT rebid by the opener.
It is alternately called two-way checkback Stayman or two-way new minor forcing because it is similar to both, but with both 2♣ and 2♦ as the asking bids.
The following sequence activates this convention:
- showing 4 of the suit
- denying 4 of the suit
- Two-way checkback, shows 5 cards in the bid major OR 4 cards in the other major. If the asking bid is 2♣, it is only invitational; if the asking bid is 2♦, it is game-forcing.
After the 2-level asking bid, opener's rebids are:
- 2♦: length in ♦s.
- 2♥/2♠: 4 cards if it is unbid OR 3 cards if it is bid (jump to 3 if maximum after 2♣)
- 2NT: no support (jump to 3NT if maximum after 2♣)
If two-way checkback is on after a 1NT rebid by opener, the following sequence is weak:
This shows at least 5 ♠s and 4 ♥s with about 6 to 9 points. With more points, 2♣ would be bid in place of 2♥.
Two-way puppet checkback Edit
Most now play 2♣ as a puppet to 2♦, enabling the use of this convention to sign off at 2♦.
Some extend this convention to all responder rebids of 2♣ and 2♦ after 3 1-level bids in an uncontested auction (i.e. 1X-1Y-1Z-2m).
See also Edit