Natural 1♠
The major suit openings show 11–16 points and 5+ cards. They can be light in late seats. I separate 1♥♠ into two chapters due to subtle differences in their continuations.
To allow a choice between 4♥ and 4♠, 1♠ - 3♥ shows an invitation with 36(xx) rather than 45(xx).
| 1♠ - | |
|---|---|
| 1NT | NAT NF, 0–3♠ |
| 2♣! | (R), FG, 0–3♠, 0–4♥ |
| 2♦! | TRF: (INV+, 5+♥) or (CONST, 6+♥) |
| 2♥! | TRF, CONST 3+♠ |
| 2♠ | PRE, 3+♠ |
| 2NT! | LIM+, 4+♠ |
| 3♣♦! | INV+, 5+#, 4+♠ |
| 3♥! | INV, 6+♥, 3=♠ |
| 3♠ | PRE, 4+♠ |
| 3NT! | COG, 33(43) |
| 4x! | SPL, 0–1#, 4+♠ |
By passed hand
A passed hand cannot force to game, so 2♣ becomes Drury. Other responses are unchanged.
A light opener passes 1NT, so opener’s rebids over it still show 11+ points.
| P - 1♠ - | |
|---|---|
| 2♣! | LIM, 3+♠ |