3rd and 4th hand can open weaker than 12HP in /1♥♠, but could also be normal/strong opening. So -2♣ response is now conventional, showing 10-11HP (after PASS).

3rd and 4th hand openings

3rd hand 5-M opening

3rd hand: Rule of 18: open /1♥♠ as of 10+HP when< HP + (length of 2 longest suits) >= 18

After PASS - (PASS) the 4th position could very well be strong. So with a 5+M we open /1M if the Rule of 18 is OK.

4th hand 5-M or 44M or 4♠ opening

4th hand: Rule of 15: open /1♥♠ as of 9+HP when HP + (length of ♠) >= 15 and length of ♥ >=3

Here we do no longer want to bid destructively. We could PASS but we presume we can play better than the enemy, so we bid /1M if Rule of 15 is OK.

Works for 11HP + 4-♠, 10HP + 5-♠, 9HP + 6+♠.

Caution: also needs 3+♥, since with very few ♥ between us, we could very well push the enemy into a makeable 2♥ contract that scores better than a PASSED OUT score. So the Rule of 15 also adheres to the Rule of 18.

Inverted Drury

Opening weaker than 12+HP in 3rd and 4th hand has a disadvantage: a partner with 10-11HP who bids this at 3-level would take the bidding too high.

So we introduce a conventional - 2♣ reply to indicate a limit (and only in a later reply establish an eventual fit).

Inverted Drury

/1♥ (in 3rd or 4th hand) - 2♣ = 10-11HP

/ 2♦ = 12-15, asks to describe 2♣ answer

/ 2NT = 16+, MF (caution! is weak 12-14 in normal bidding)

/ 2♥ = (9)10-11, 5+♥, NF

/ 2♠ = 16+HP, MF (reverse)

/1♠ (in 3rd or 4th hand) - 2♣ = 10-11HP

/ 2♦ = 12-15, asks to describe 2♣ answer

/ 2NT = 16+, MF (caution! is weak 12-14 in normal bidding)

/ 2♠ = (9)10-11, 5+♠, NF

/ 2♥ = (9)10-11, 5+♠, 4+♥, NF

Fits with external 5+ discard suit are bid directly:

/1♥ - 2♠3♣♦ = 10-11, 4+♥ (fit), 5+♠♣♦

/1♠ - 3♣♦♥ = 10-11, 4+♠ (fit), 5+♣♦♥

Side Effects

This also implies that (again in 3rd or 4th hand)

/1♥ - 1♠2♦ = NF

/1♠ - 2♦♥ = NF

Further bidding

Caution! minimum could be 12-13HP, so answerer must not jump.

/1♠ - 2♣ / 2♦ = 10-11

- 2♥ = 4-♥ (with a 5+♥ and 10-11HP, the first answer would have been - 2♥ directly)

/ PASS = 12-13, 4-♥

/ 2♠ = 12-13, 6+♠, 0-3♥

/ 2NT = 12-13, 0-3♥

/ 3♣♦ = 14-15 (16+ would have caused a / 3♣♦ MF rebid directly)

/ 3♥ = 14-15, 4-♥

/ 3♠ = 14-15, 4-♠

/ 3NT = 14-15, 0-3♥

- 2♠ = 3+♠, no 4-♥

/ PASS = 12-13

/ 2NT = 14-15

/ 3♣♦ = 14-15 (16+ would have caused a / 3♣♦ MF rebid directly)

/ 3♠ = 14-15, 6+♠

- 2NT = 11, 0-2♠, 0-3♥, stops in ♣♦

- 3♣♦ = 11, 5+♣♦, 0-2♠, 2-3♥ incl stop, no stop in other m, NF

- 3♥ = 11, 5+♥, 0-2♠