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.
| 1♦-1♥ 1♠- | 12–17, 4+♠ |
| 1NT | MIN, 0–3♠, 4–5♥, 0–3♦ |
| 2♣! | BTU CB, F1 |
| 2♦! | FG CB |
| 2♥ | INV, 5+♥ |
| 2♠ | INV, 4+♠ |
| 2NT! | TRF, PRE or FG, 6+♣ |
| 3♣ | S/T, 5+♣, 5+♥ |
| 3♦ | S/T, 4+♦, 5+♥ |
| 3♥ | S/T, 6+♥ |
| 3♠ | S/T, 4+♠ |
| 1♦-1♥ 1♠-1NT | NAT MIN |
| 2♣ | NF, 4=♣ |
| 2♦ | NF, 6+♦ |
| 2♥ | INV, 3=♥ |
| 2♠ | INV, 5+♠, 6+♦ |
| 2NT | NAT INV |
| 3♣ | FG, 4=♣ |
| 3♦ | FG, 6+♦ |
| 3♥ | FG, 3=♥ |
| 1♦-1♥ 1♠-2♣ | BTU CB |
| 2♦ | MIN |
| 2♥ | MAX, 3=♥ |
| 2♠ | MAX, at most partial stop in ♣ |
| 2NT | MAX, likely stop in ♣ |
| 3♣ | MAX, 4054 |
| 3♦ | MAX, 6+♦ |
| 1♦-1♥ 1♠-2♣ 2♦- | MIN |
| 2♥ | S/O, UNBAL 5+♥ |
| 2♠ | S/O, 4+♠ |
| 2NT | BAL INV |
| 3♣ | INV, 6+♣ |
| 3♦ | INV, 4+♦ |
| 3♥ | INV, S-SOL 6+♥ |
| 3♠ | INV, 4+♠, 5+♥ |
| 1♦-1♥ 1NT- | BAL MIN |
| 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, 4+♦, 5+♥ |
| 3♥ | S/T, 6+♥ |
| 3♠! | SPL, 0–1♠, 6+♥ |
| 4♣! | SPL, 0–1♣, 6+♥ |
| 4♦ | FG, 4+♦, 6+♥ |
| 1♦-1♥ 1NT-2♣ 2♦- | P/C |
| 2♥ | S/O, 5+♥ |
| 2♠ | INV, 4+♠, 6+♥ |
| 2NT | BAL INV |
| 3♣ | INV, 6+♣ |
| 3♦ | INV, 4+♦ |
| 3♥ | INV, S-SOL 6+♥ |
| 1♦-1♠ 1NT- | BAL MIN |
| 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♦ | FG, 4+♦, 6+♠ |
| 4♥! | SPL, 0–1♥, 6+♠ |
| 1♦-1♠ 1NT-2♣ 2♦- | P/C |
| 2♥ | MIN, 4+♥, 5+♠ |
| 2♠ | S/O, 5+♠ |
| 2NT | BAL INV |
| 3♣ | INV, 6+♣ |
| 3♦ | INV, 6+♦ |
| 3♥ | INV, 5+♥, 5+♠ |
| 3♠ | INV, S-SOL 6+♠ |