Natural 1♥-1♠

As the opening is limited to 12–17, the reverses are not forcing. The reverses show a maximum 5+ 5+ two suiter.

1♥-1♠-4+♠
1NTBAL 12–14
2♣♦NF, 4+#
2♥MIN, 12–14, 6+♥
2♠MIN, 12–14, 4+♠
2NTBAL INV, 15–17
3♣♦INV, 15–17, 5+#
3♥INV, 15–17, 6+♥
3♠INV, 15–17, 4+♠
3NTTo play
4♣♦!SPL, 0–1#, 4+♠
4♥♠To play

BTU 3-way checkback

BTU checkback is also in effect after 1♥-1♠-1NT, similar to 1♦-1M-1NT. 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♠-1NT-BAL MIN
2♣!BTU CB, F1
2♣-2♦P/C
2♣-2♥!P/C, 4+♦
2♣-2♠!MAX, 3=♠
2♦!FG CB
2♥INV, 2–3♥
2♠INV, 5+♠
2NT!TRF, PRE or FG, 6+♣
3♣S/T, 5+♣, 5+♠
3♦S/T, 5+♦, 5+♠
3♥S/T, 3+♥
3♠S/T, 6+♠
1♥-1♠; 1NT-2♣; 2♦-P/C
2♥S/O, 2+♥
2♠S/O, 5+♠
2NTBAL INV
3♣INV, 6+♣
3♦INV, 6+♦
3♥STR INV, 3+♥
3♠INV, S-SOL 6+♠