We use BTU-style 3-way checkback to an XYZ auction. There are 3 artificial
relays in the 3-way checkback:
- 2♣: several variants:
- to play 2X
- strongly shaped invitation
- balanced invitation or choice of games
- 2♦: game-forcing checkback, usually a choice of games
- 2NT: transfer to clubs
As a corollary, natural 2X are wide-range invitations and 3X become slam tries.
In this particular case of BTU checkback, opener can pass 1♣-1♥ 1♠-2♣ with
minimum long clubs. Otherwise, BTU checkback is forcing.
| 1♣-1♥ 1♠- | F, 4+♠ |
|---|
| 1NT | MIN, 7–10, 0–3♠, 4–5♥ |
| 2♣! | BTU CB, NF |
| 2♦! | FG CB |
| 2♥ | INV, 5+♥ |
| 2♠ | INV, 4+♠ |
| 2NT | TRF, PRE or FG, 6+♣ |
| 3♣ | S/T, 5+♣, 5+♥ |
| 3♦ | S/T, 5+♦, 5+♥ |
| 3♥ | S/T, 6+♥ |
| 3♠ | S/T, 4+♠ |
| 3NT | 12–15, 0–3♠, 4=♥, 0–5♦, 0–5♣ |
| 1♣-1♥ 1♠-1NT | NAT MIN |
|---|
| 2♣ | NF, 12–15, 5+♣ |
| 2♦! | 4SF1, INV+, 0–2♥ |
| 2♥ | INV, 3=♥ |
| 2♠ | FG, 5+♠ |
| 2NT | INV, 16–17, 0–2♥ |
| 3♣ | FG, 6+♣ |
| 3♦ | FG, 6+♦ |
| 3♥ | FG, 5+♠, 3=♥ |
| 1♣-1♥ 1♠-2♣ | BTU CB |
|---|
| P | S/O, 12–13, 6+♣ |
| 2♦! | MIN, 12–15 |
| 2♥ | INV, 3=♥ |
| 2♠ | FG, 5+♠, 0–2♥ |
| 2NT | FG, 4=♠ |
| 3♣ | INV, 16–17, 5+♣, 0–2♥ |
| 3♦ | FG, 5+♦ |
| 3♥ | FG, 5+♠, 3=♥ |
| 3♠! | FG, 5+♣, 4=♠, 0–2♥ |
| 3NT | Mild S/T, 21–23, 4=♠ |
| 1♣-1♥ 1♠-2♣ 2♦- | MIN, 12–15 |
|---|
| P | MIN, 5+♦ |
| 2♥ | UNBAL MIN, 5+♥ |
| 2♠ | MIN, 4+♠ |
| 2NT | BAL INV |
| 3♣ | INV, 6+♣ |
| 3♦ | INV, 6+♦ |
| 3♥ | INV, S-SOL 6+♥ |
| 3♠ | INV, 4+♠, 5+♥ |
| 1♣-1♥ 1NT- | BAL 12–14 |
|---|
| 2♣! | BTU CB, F1 |
| 2♣ 2♦! | P/C |
| 2♣ 2♥ | MAX, 3=♥ |
| 2♦! | FG CB |
| 2♥ | INV, 5+♥ |
| 2♠ | INV, 4+♠ |
| 2NT | TRF, PRE or FG, 6+♣ |
| 3♣ | S/T, 5+♣, 5+♥ |
| 3♦ | S/T, 5+♦, 5+♥ |
| 3♥ | S/T, 6+♥ |
| 3♠! | SPL, 0–1♠, 6+♥ |
| 3N | 12–15, 4=♥ |
| 4♣! | SPL, 0–1♣, 6+♥ |
| 4♦! | SPL, 0–1♦, 6+♥ |
| 1♣-1♥ 1NT-2♣ 2♦- | BAL 12–14, P/C |
|---|
| 2♥ | S/O, 5+♥ |
| 2♠ | INV, 4+♠, 6+♥ |
| 2NT | BAL INV |
| 3♣ | INV, 6+♣ |
| 3♦ | INV, 6+♦ |
| 3♥ | INV, S-SOL 6+♥ |
| 3NT | Choice of games, 5♥(332) |
| 1♣-1♠ 1NT- | BAL 12–14 |
|---|
| 2♣! | BTU CB, F1 |
| 2♣ 2♦! | P/C |
| 2♣ 2♥ | MAX, 4=♥ |
| 2♣ 2♠ | MAX, 3=♠ |
| 2♦! | FG CB |
| 2♥ | INV, 4+♥, 5+♠ |
| 2♠ | INV, 5+♠ |
| 2NT | TRF, PRE or FG, 6+♣ |
| 3♣ | S/T, 5+♣, 5+♠ |
| 3♦ | S/T, 5+♦, 5+♠ |
| 3♥ | S/T, 5+♥, 5+♠ |
| 3♠ | S/T, 6+♠ |
| 3NT | 12–15, 4=♠ |
| 4♣! | SPL, 0–1♣, 6+♠ |
| 4♦! | SPL, 0–1♦, 6+♠ |
| 4♥! | SPL, 0–1♥, 6+♠ |
| 1♣-1♠ 1NT-2♣ 2♦- | BAL 12–14, P/C |
|---|
| 2♥ | INV, 5+♥, 5+♠ |
| 2♠ | S/O, 5+♠ |
| 2NT | BAL INV |
| 3♣ | INV, 6+♣ |
| 3♦ | INV, 6+♦ |
| 3♥ | INV, 4+♥, 6+♠ |
| 3♠ | INV, S-SOL 6+♠ |
| 3NT | Choice of games, 5♠(332) |