XYZ is in effect whenever our side has made 3 (or more) bids at the one level, and it’s Responder’s turn to
bid:
1♣-1♦-1♥, 1♣-1♦-1♠, 1♣-1♦-1NT, 1♣-1♥-1♠, 1♣-1♥-1NT,
1♣-1♠-1NT, 1♦-1♥-1♠, 1♦-1♥-1NT, 1♦-1♠-1NT, 1♥-1♠-1NT, or even 1♣-1♦-1♥-1♠-1NT.
- Any direct bid on the two-level is a sign-off.
- 2♣ by the responder is invitational (or weak on diamonds), asking the
opener to bid 2♦.
- 1♦-1♥-1NT-2NT is a relay(!) to
sign-off in clubs.
- 1♦-1♥-1NT-2♣-2♦-2NT is an invitation to 3NT.
- 2♦ by the responder is game forcing. This artificially tells your
partner that you have 13+ points.
- With less than invitational values, Responder may rebid a 5+ card major suit to play.
- When Responder has more than enough for the game and a long, strong 6+ card suit and is considering a
slam, he does not use the 2♦ game force. Instead, he jumps to the 3
level in his suit.
- XYZ replaces two-level new minor forcing.
- XYZ is ON when opponents interfere.