[Dr Abc]

Minor Suit Forcing is a bridge bidding system designed for advanced bridge players. It is the key that both 1♣ and 1♦ openings are forcing bids. While 1♣ opening has a broad HCP range, 1♦ opening shows a strong hand with 16+ HCP.

Opening Bids

1NT:
15-17 HCP, balanced or 5-card minor of 5332 shape

2NT:
21-22 HCP, balanced or 5-card minor of 5332 shape

2♣:
13-15 HCP, no 4-card major, no 5-card ♦, 5+ ♣ suit, not 5332 shape

2♦:
13-15 HCP, no 4-card major, 5+ ♦ suit, not 5332 shape

1♥:
11-15 HCP, 5+ ♥ suit, ♥ is longer than ♠ suit

1♠:
11-15 HCP, 5+ ♠ suit, ♠ is not shorter than ♥ suit

1♦:
18-20 HCP, balanced or 5-card minor of 5332 shape
23-24 HCP, balanced or 5-card minor of 5332 shape
16-18 HCP, no 5-card major, 5+ minor suit, not 5332 shape
19-21 HCP, no 5-card major, either 5+ minor suit or 4441 shape
22-24 HCP, no 5-card major, 5+ minor suit, not 5332 shape
25+ HCP, no 5-card major, either 5+ minor suit or 4441 shape

1♣:
11-12 HCP, 4-card major or 5+ minor suit including 5332 shape
13-14 HCP, 4-card major or balanced or 5-card minor of 5332 shape
15 HCP, 4-card major, either 5+ minor suit or 4441 shape
16+ HCP, 5+ major suit
16-18 HCP, 4441 shape
22-24 HCP, 4441 shape
25+ HCP, balanced shape

All higher suit openings are weak and preemptive. The 3NT opening shows less than 16 HCP of a strong minor suit with 9 winners.

After 1NT, 2NT, 2♣, and 2♦ Openings

Stayman and Transfers are well-known responses to 1NT and 2NT openings and they are also adopted here.

The responses to 2♣ and 2♦ openings are simple and straightforward. Since the opener has no 4-card major, there is no need to seek for a 4-4 major match. Therefore

2♥/2♠:
9+ HCP, 5+ ♥/♠ suit, asking for opener’s 3 ♥/♠-card support

Additionally, the 2♣/2♦ opener only has a limited 13-15 HCP range, any other response is either game invitational or game sign-off.

After 1♥ and 1♠ Openings

In terms of responding to 1♥ and 1♠ openings, Minor Suit Forcing has two important differences from most other bidding systems such as Sayc, Two-Over-One, and Precision.

1) 1♠ response over 1♥ opening requires 5+ ♠ cards
2) 1NT is not forcing, while 2♣ and 2♦ responses are

Responses over 1♥ opening
1♠:
9-11 HCP, no 3 ♥ cards, 5+ ♠ suit
12+ HCP, 5+ ♠ suit (may have 3+ ♥ cards)

1NT:
9-11 HCP, no 5 ♠ cards, either no 2 ♥ cards or 2 ♥ without 4 ♠ cards

2♣:
9-11 HCP, 2 ♥ with 4 ♠ cards
12+ HCP, no 3 ♥ cards, 4 ♠ cards

2♦:
12+ HCP, no 3 ♥ cards, neither 4 ♠ cards

All other responses are more or less supporting the opening ♥ suit.

After 2♣ response:
2♦:
11-13 HCP, 5+ ♥ suit, no 4 ♠ cards, forcing

2♥:
14-15 HCP, 5+ ♥ suit, no 4 ♠ cards, non-forcing

2♠:
11-13 HCP, 5+ ♥ suit with 4 ♠ cards, non-forcing

2NT:
14-15 HCP, 5 ♥ suit with 4 ♠ cards, forcing

3H:
14-15 HCP, 6+ ♥ suit with 4 ♠ cards, forcing

3♠:
14-15 HCP, 6+ ♥ suit with 5+ ♠ suit, forcing

Responses over 1♠ opening
1NT:
9-11 HCP, no 2 ♠ cards or 2 ♠ without 4 ♥ cards

2♣:
9-11 HCP, 2 ♠ with 4+ ♥ cards
12+ HCP, no 3 ♠ cards, 4 ♥ cards

2♦:
12+ HCP, no 3 ♠ cards, neither 4 ♥ cards

2♥:
12+ HCP, 5+ ♥ suit (may have 3+ ♠ cards)

All other responses are more or less supporting the opening ♠ suit.

After 2♣ response:
2♦:
11-13 HCP, 5+ ♠ suit, no 4 ♥ cards, forcing

2♥:
11-13 HCP, 5+ ♠ suit with 4 ♥ cards, non-forcing

2♠:
14-15 HCP, 5+ ♠ suit, no 4 ♥ cards, non-forcing

2NT:
14-15 HCP, 5 ♠ suit with 4 ♥ cards, forcing

3♥:
14-15 HCP, 5+ ♠ suit with 5+ ♥ cards, forcing

3♠:
14-15 HCP, 6+ S suit with 4+ ♥ suit, forcing

Opener's rebids after 2♦ response
Level-2 opening suit:
11-12 HCP, 6+ opening suit, non-forcing

Level-2 other suit:
11-12 HCP, 5 opening suit with other 4+ card suit, non-forcing

2NT:
11-12 HCP, 5 opening suit, either 5332 shape or other 4+ card suit, non-forcing

Level-3 opening major:
13-15 HCP, 6+ opening suit, forcing

Level-3 other suit:
13-15 HCP, 5+ opening suit with other 4+ card suit, forcing

3NT:
13-15 HCP, 5 opening suit of 5332 shape

Responses Over 1♣ and 1♦ Openings

For a given strong hand, the opener can choose one of two forcing openings 1♣ and 1♦ to start the bidding process.
As a result, the opener is able to describe the hand, almost in the first rebid, very precisely about the hand strength within 3 HCP range as well as the hand shape.

To describe the hand shape, we normally consider the following order
1) 5+ major suit
2) 4 card major, unbalanced (i.e. with 5+ minor suit or 4441 shape)
3) Balanced (i.e. 4333 or 4432 shape) with or without 4 card major
4) No 4 card major, 5 card minor of 5332 shape
5) No 4 card major, 5+ minor suit, not 5332 shape

For the first response of 1♣ and 1♦ openings, the responder has one of the following three things to do
1) Wait – a relatively weak hand waiting for the opener’s rebid
2) Show 5+ major – an average to strong hand willing to know the opener’s major support
3) Force a game – a strong hand enough to reach a game, although there is no 5 card major

Responses over 1♣ opening
1♦ (wait):
0-8 HCP, any
9-12 HCP, no 5-card major

1♥ (show 5+ ♥ suit):
9+ HCP, 5+ H suit, H longer than S

1♠ (show 5+ ♠ suit):
9+ HCP, 5+ S suit, S not shorter than H

1NT (force a game):
13+ HCP, balanced or 5-card minor of 5332 shape

2♣ (force a game):
13+ HCP, no 5 card major, 4+ ♣ suit, unbalanced (may have 4-card major)

2♦ (force a game):
13+ HCP, no 5 card major, 4+ ♦ suit, unbalanced (may have 4-card major)

Responses over 1♦ opening
1♥ (wait):
0-5 HCP, any
6-8 HCP, no 5-card major

1♠ (show 5+ major):
6+ HCP, 5+ major suit (♥ and/or ♠)

1NT (force a game):
9+ HCP, balanced or 5-card minor of 5332 shape

2♣ (force a game):
9+ HCP, no 5 card major, 4+ ♣ suit, unbalanced (may have 4-card major)

2♦ (force a game):
9+ HCP, no 5 card major, 4+ ♦ suit, unbalanced (may have 4-card major)

It is to mention that no first response of 1♣ and 1♦ openings is higher than 2♦ bid and interestingly, all first responses except for 1♦ over 1♣ are also forcing bids.

After 1♣ Opening and 1♦ Response

Any 1♣ opening hand can be divided into one of the following 6 groups
1) 11-14 HCP, no 4 card major
2) 11-15 HCP, 4 card major or 16-18 HCP, either 5+ major suit or 4441 shape
3) 19-21 HCP, 5+ major suit
4) 22+ HCP, 5+ major suit or 9+ winners
5) 22-24 HCP, 4441 shape
6) 25+ HCP, balanced

The opener uses Pass and all possible bids from 1♥ up to 4♣ along with 4NT to describe the hand

Opener’s rebids – group 1
Pass:
11-12 HCP, no 4 card major, 5+ ♦ suit

2♣:
11-12 HCP, no 4 card major, 5+ ♣ suit

1NT:
13-14 HCP, no 4 card major, balanced or 5 minor suit of 5332 shape

The responder can further bid 2♥ or 2♠ to sign-off and bid 2NT to invite for 3NT.
There should be no direct jump to 3NT, unless the responder holds 11-12 HCP with a good minor suit.

Opener’s rebids – group 2
1♥:
11-15 HCP, 4 ♥ cards
16-18 HCP, 4 ♥ cards, 4441 shape
16-18 HCP, 5+ ♥ suit, ♥ longer than ♠

1♠:
11-15 HCP, 4 ♠ cards, no 4 ♥ cards
16-18 HCP, 4 ♥ cards, singleton ♥, 4441 shape
16-18 HCP, 5+ ♠ suit, ♠ not shorter than ♥

As further responses, the responder should raise or jumped-raise the opener's major suit with 6+ HCP, 4+ major support.
The responder can also rebid 1♠ over opener’s 1♥ with 6-8 HCP, 4+ ♠ or 9-12 HCP, 4 ♠ cards.
Responder’s 1NT rebid shows 6-10 HCP, while 2♣/2♦ rebids require 11-12 HCP, 4+ ♣/♦ cards.

The opener needs to rebid the same major in order to show 16-18 HCP, 5+ major suit.
If the opener further bids the other major as new suit, it means 16-18 HCP, 5+ old and 4+ new major suits.

Opener’s rebids – group 3
2♥:
19-21 HCP, 5+ ♥ suit, ♥ longer than ♠

2♠:
19-21 HCP, 5+ ♠ suit, ♠ not shorter than ♥

These two opener's jumped major suit bids are actually non-forcing.

Opener’s rebids – group 4
3♥:
16-21 HCP, 6+ ♥ suit, 9 winners
22-24 HCP, 6+ ♥ suit

3♠:
16-21 HCP, 6+ ♠ suit, 9 winners
22-24 HCP, 6+ ♠ suit

2NT:
22-24 HCP, 5 major cards, no 9 winners, forcing

3♣:
25+ HCP, 5+ major suit or 10+ winners, game forcing

Opener’s rebids – group 5
2♦:
22-24 HCP, 4441 shape, forcing

The responder’s rebids are specifically designed as follows
--2♥: no 4 ♥ cards
--2♠: 4+ ♥ cards, no 4 ♠ cards
--2NT: 4+ ♥ and 4+ ♠ cards

Opener’s rebids – group 6
3♦:
25-28 HCP, 4 card major, 4432 shape, forcing

3NT:
25-28 HCP, 4333 or no 4 card major, 4432 shape

4♣:
29-30 HCP, balanced, direct asking for Ace

4NT:
31+ HCP, balanced, direct asking for Ace

After 1♦ Opening and 1♥ Response

Any 1♦ opening hand can be divided into one of the following 6 groups
1) 18-20 or 22-23 HCP, balanced or 5+ minor suit of 5332 shape
2) 16-18 HCP, no 5 card major, 5+ minor suit, not 5332 shape
3) 19-21 HCP, no 5 card major, either 5+ minor suit (not 5332) or 4441 shape
4) 22-24 HCP, 4 card major, 5+ minor suit
5) 25+ HCP, either 4 card major with 5+ minor suit or 4441 shape
6) 25+ HCP, no 4 card major, 5+ minor suit

The opener uses all possible bids from 1♠ up to 4♦ along with 4NT, 5♣ and 5♦ to describe the hand

Opener’s rebids – group 1
1NT:
18-20 HCP, balanced or 5 minor suit of 5332 shape

2NT:
23-24 HCP, balanced or 5 minor suit of 5332 shape

The responder’s rebids are exactly the same as those responses used respectively to direct 1NT and 2NT openings.

Opener’s rebids – group 2
2♣:
16-18 HCP, no 5 major, 5+ ♣ suit, not 5332 shape

2♦:
16-18 HCP, no 5 major, 5+ ♦ suit, not 5332 shape

These two opener’s minor suit bids are basically discouraging.
However, the responder can bid 2♥/2♠ to show 6-8 HCP, 4 ♥/♠ cards looking for a 4-4 major match.
Holding 6-7 HCP, the responder can also bid 2NT with major stopper or raise the opener’s minor suit for 3NT try.
If the responder has a good 8 HCP with major stoppers, it is also possible to directly jump to 3NT.

Opener’s rebids – group 3
1♠:
19-21 HCP, no 5 card major, unbalanced shape, forcing

This opener’s rebid is virtual and forcing. The responder needs to rebid one of the following options
--1NT: 0-3 HCP, any shape
--2♣: 4-8 HCP, no 5 card major, 3+ ♣ cards (may have single 4 card major)
--2♦: 4-8 HCP, no 5 card major, 4+ ♦ cards (may have single 4 card major)
--2♥: 4-5 HCP, 5+ ♥ suit
--2♠: 4-5 HCP, 5+ ♠ suit
--2NT: 4-5 HCP, both 4 ♥ and 4 ♠ cards, 4432 or 4441 shape
--3♣: 6-8 HCP, no 4 card major, 5+ ♣ suit
--3♦: 6-8 HCP, no 4 card major, 5+ ♦ suit
--3NT: 6-8 HCP, both 4 ♥ and 4 ♠ cards, 4432 or 4441 shape

Opener’s rebids – group 4
2♥:
22-24 HCP, 4 ♥ cards, 5+ minor suit

2♠:
22-24 HCP, 4 ♠ cards, no 4 ♥ cards, 5+ minor suit

These two opener's major suit bids are actually non-forcing.
However, the responder can deny the major by bidding another suit or 2NT in order to find a different suit fit.

Opener’s rebids – group 5
3♥:
25+ HCP, 4 ♥ cards, either 5+ minor suit or 4441 shape, game forcing

3♠:
25+ HCP, 4 ♠ cards, no 4 ♥ cards, either 5+ minor suit or singleton ♥, 4441 shape, game forcing

Opener’s rebids – group 6
3♣:
22-24 HCP, no 4 card major, 5+ ♣ suit, not 5332 shape

3♦:
22-24 HCP, no 4 card major, 5+ ♦ suit, not 5332 shape

3NT:
16-21, no 4 card major, 7+ minor suit, 9 winners
22+ HCP, no 4 card major, 6+ minor suit, 9 winners

4♣:
25+ HCP, no 4 card major, 6+ ♣ suit, side-suit unstopped

4♦:
25+ HCP, no 4 card major, 6+ ♦ suit, side-suit unstopped

5♣:
25+ HCP, no 4 card major, 6+ ♣ suit, 11 winners

5♦:
25+ HCP, no 4 card major, 6+ ♦ suit, 11 winners

4NT:
25+ HCP, no 4 card major, 6+ minor suit, direct asking for Ace

After 1♣ Opening and 1♥/1♠ Response

The opener with the same opening hand may need a different rebid after 1♥/1♠ response comparing to 1♦ response.

All possible opener’s rebids are divided into three groups as shown below
1) Direct major suit raise
2) Implied major suit support
3) Major suit denied or support postponed

Opener’s rebids – group 1
Raise to 2♥/♠:
11-14 HCP, counting the hand shape 11-14 points, 3 or 4 ♥/♠ support

Raise to 3♥/♠:
13-15 HCP, counting the hand shape 15-16 points, 3 or 4 ♥/♠ support

Raise to 4♥/♠:
14-15 HCP, counting the hand shape 17+ points, 3 or 4 ♥/♠ support

Opener’s rebids – group 2
3♣:
16-18 HCP, 4+ ♥/♠ support, singleton ♣, forcing

3♦:
16-18 HCP, 4+ ♥/♠ support, singleton ♦, forcing

3♥ (after 1♠ response):
16-18 HCP, 4+ ♠ support, singleton ♥, forcing

3♠ (after 1♥ response):
16-18 HCP, 4+ ♥ support, singleton ♠, forcing

3NT:
16-18 HCP, 5+ ♥/♠ support, no singleton, forcing

4♣:
19+ HCP, 4+ ♥/♠ support, direct asking for Roman keys

Opener’s rebids – group 3
1♠ (after 1♥ response):
11-15 HCP, no 3 ♥ cards, 4 ♠ cards

1NT (after 1♥ response):
13-14 HCP, no 3 ♥ cards, no 4 ♠ cards, either balanced or 5 minor of 5332 shape

1NT (after 1♠ response):
11-12 HCP, no 3 ♠ cards, 4 ♥ cards
13-14 HCP, no 3 ♠ cards, either balanced or 5 minor of 5332 shape
15 HCP, no 3 ♠ cards, 4 ♥ cards, unbalanced

2♣:
11-12 HCP, no 3 ♥/♠ cards, no other 4 card major, 5+ ♣ suit

2♦:
11-12 HCP, no 3 ♥/♠ cards, no other 4 card major, 5+ ♦ suit

2♥ (after 1♠ response):
16+ HCP, 5+ ♥ suit (may have 3+ ♠ support)

2♠ (after 1♥ response):
16+ HCP, 5+ ♠ suit (may have 3+ ♥ support)

2NT:
16-18 HCP, single ♥/♠, 4441 shape
22-24 HCP, single ♥/♠, 4441 shape
25+ HCP, balanced

After 1♦ Opening and 1♠ Response

The 1♠ response over 1♦ opening shows that the responder holds at least one 5+ major suit.
Without knowing the real major, the opener keeps many rebids as used after 1♥ response while giving the responder a chance to further clarify.

All possible rebids from the opener are shown as below
1NT:
18-20 HCP, balanced or 5 minor suit of 5332 shape
19-21 HCP, no 5 card major, unbalanced

2♣:
16-18 HCP, no 5 major, 5+ ♣ suit, not 5332 shape

2♦:
16-18 HCP, no 5 major, 5+ ♦ suit, not 5332 shape

2♥:
22+ HCP, 4 ♥ cards, 5+ minor suit

2♠:
22+ HCP, 4 ♠ cards, no 4 ♥ cards, 5+ minor suit

2NT:
23-24 HCP, balanced or 5 minor suit of 5332 shape

3♣:
22+ HCP, no 4 card major, 5+ ♣ suit

3♦:
22+ HCP, no 4 card major, 5+ ♦ suit

The responder further bids either 2♥/2♠ (if applicable) or 3♥/3♠ to tell the real 5+ major suit.

After 1♣/1♦ Opening and Game Forcing Response

After 1♣/1♦ opening, all three responses 1NT, 2♣, and 2♦ show the responder’s hand lack of 5-card major but strong enough to play a game.

The subsequent bidding process is basically to answer two questions
1) What is the best game contract and how to reach it?
2) Is the strength combining both hands enough for a slam and how to try it?

Opener’s rebids after 1NT over 1♣
2♣:
11-12 HCP, no 5 card major, 3+ ♣ cards (may have 4 card major)

2♦:
11-12 HCP, no 5 card major, 3+ ♦ cards (may have 4 card major)

2♥:
13-15 HCP, 4 ♥ cards, unbalanced
16-18 HCP, 4 ♥ cards, 4441 shape
16-18 HCP, 5+ ♥ suit, ♥ longer than ♠

2♠:
13-15 HCP, 4 ♠ cards, unbalanced
16-18 HCP, 4 ♠ cards, singleton ♥, 4441 shape
16-18 HCP, 5+ ♠ suit, ♠ not shorter than ♥

2NT:
13-14 HCP, balanced (may have 4 card major) or 5 minor suit of 5332 shape

3♣:
22-24 HCP, 4 ♣ cards, 4441 shape

3♦:
22-24 HCP, 4 ♦ cards, singleton ♣, 4441 shape

3♥:
19+ HCP, 5+ ♥ suit, ♥ longer than ♠

3♠:
19+ HCP, 5+ ♠ suit, ♠ not shorter than ♥

3NT (very unlikely):
25+ HCP, balanced, forcing

Opener’s rebids after 2♣/2♦ over 1♣
2♦ (after 2♣ response):
11-12 HCP, no 4 card major, 5+ ♦ suit

3♣ (after 2♣ response):
11-12 HCP, no 4 card major, 5+ ♣ suit
13-15 HCP, no 4 card major, 3+ ♣ cards, no major stopper

3♣ (after 2♦ response):
11-12 HCP, no 4 card major, 5+ ♣ suit

3♦ (after 2♦ response):
11-12 HCP, no 4 card major, 5+ ♦ suit
13-14 HCP, no 4 card major, 3+ ♦ cards, no major stopper

2♥:
11-15 HCP, 4 ♥ cards
16-18 HCP, 5+ ♥ suit or 4 ♥ cards, 4441 shape
22-24 HCP, 4 ♥ cards, 4441 shape

2♠:
11-15 HCP, no 4 ♥ cards, 4 ♠ cards
16-18 HCP, 5+ ♠ suit or 4 ♠ cards, singleton ♥, 4441 shape
22-24, 4 ♠ cards, singleton ♥, 4441 shape

2NT:
13-14 HCP, no 4 major cards, balanced or 5 minor suit of 5332 shape, with major stoppers

3♥:
19+, HCP 5+ ♥ suit, ♥ longer than ♠

3♠:
19+ HCP, 5+ ♠ suit, ♠ not shorter than ♥

3NT (very unlikely):
25+ HCP, balanced, forcing

Opener’s rebids after 1NT over 1♦
2♣:
16-18 HCP, 5+ ♣ suit, unbalanced (may have 4 card major)
19-21 HCP, no 4 card major, 5+ ♣ suit

2♦:
16-18 HCP, 5+ ♦ suit, unbalanced (may have 4 card major)
19-21 HCP, no 4 card major, 5+ ♦ suit

2♥:
19-21 HCP, 4 ♥ cards, unbalanced

2♠:
19-21, 4 ♠ cards, no 4 ♥ cards, unbalanced

2NT:
18-20 HCP, balanced (may have 4 card major) or 5 minor suit of 5332 shape
23-24 HCP, 4 card major, balanced

3♣:
22+ HCP, no 4 card major, 5+ ♣ suit

3♦:
22+ HCP, no 4 card major, 5+ ♦ suit

3♥:
22+ HCP, 4 ♥ cards, unbalanced

3♠:
22+ HCP, 4 ♠ cards, no 4 ♥ cards, unbalanced

3NT:
23-24 HCP, no 4 card major, balanced or 5 minor suit of 5332 shape, non-forcing

Opener’s rebids after 2♣/2♦ over 1♦
2♦ (after 2♣ response):
16-21 HCP, no 4 card major, no 4 ♣ cards, 5+ ♦ suit

3♣ (after 2♣ response):
16-21 HCP, no 4 card major, 4+ ♣ cards, unbalanced

3♦ (after 2♣ response):
22+ HCP, no 4 card major, no 4 ♣ cards, 5+ ♦ suit

3♣ (after 2♦ response):
16+ HCP, no 4 card major, no 4 ♦ cards, 5+ ♣ suit

3♦ (after 2♦ response):
16-21 HCP, no 4 card major, 4+ ♦ cards, unbalanced

2♥:
16-21 HCP, 4 ♥ cards, unbalanced

2♠:
16-21 HCP, 4 ♠ cards, no 4 ♥ cards, unbalanced

2NT:
18-20 HCP, balanced (may have 4 card major)
23-24 HCP, 4 card major, balanced

3♥:
22+ HCP, 4 ♥ cards, unbalanced

3♠:
22+ HCP, 4 ♠ cards, no 4 ♥ cards, unbalanced

3NT:
23-24 HCP, no 4 card major, balanced or 5 minor suit of 5332 shape, non-forcing

4♣:
22+ HCP, no 4 card major, 4+ ♣/♦ cards, direct asking for Roman keys

Responder’s further responses

To continue the bidding process, the responder has a unified approach to follow
Over opener’s 2♣/2♦:
– bid 2♥ or 2♠ with 4 ♥ or 4 ♠ cards
– raise to 3♣/3♦ with 4+ ♣/♦ card support
– bid the other minor with 4+ minor cards
– bid 2NT otherwise

Over opener’s 2♥/2♠:
– raise to 3♥/3♠ with 4 ♥/♠ card support
– bid the other major with 4 major cards
– bid (another) minor with 4+ minor cards
– bid 2NT otherwise

Over opener’s 2NT:
– bid 3♥ or 3♠ with 4 ♥ or 4 ♠ cards
– bid (another) minor with 4+ minor cards
– bid 3NT otherwise

Over opener’s 3♣/3♦:
– bid 3♥ or 3♠ with 4 ♥ or 4 ♠ cards
– start slam try with 4+ ♣/♦ card support, if possible
– bid 3NT otherwise

Over opener’s 3♥/3♠:
– start slam try with 4 ♥/♠ card support, if possible
– bid the other major with 4 major cards
– bid 3NT otherwise

[pescetom]

Non-natural systems have their own forum, maybe someone could move this.
I have no related expertise, but FWIW at first sight 2♣/♦ look underloaded.

[mycroft]

...and done.

I would enjoy playing my strong club defence against 1♦ and my strong NT defence (basically, would be closer to KitW's "grunt defence") against 1♣.

That's without checking the probabilities. I'll probably run up a script to do that, to see if my gut feel is right.

[mycroft]

Okay, I think there are no bugs in my simulator - I no longer have a hand that either has no bids (but is a non-preempt opener) or more than one opening bid. Frankly, with a system like this, I'm quite impressed that there aren't hands that legitimately fit two opening bids; in that it's well-designed.

(Please note, I believe that OP's native language is not English: what OP means by "5+ minor suit but 5332 shape" is "5+m but *not* 5332 shape". Took me a while to work that out. This is not a criticism; when my Italian or Spanish is this good, I get to criticize. Just for others reading.)

Sample output (the categories are in the same order as in the OP, for the 1m openings):

1C:
    HCP11_12: 4656
    HCP13_14: 3366
    HCP15: 269
    STR_M: 1648
    MED_ROMAN: 118
    STR_ROMAN: 7
    HUGE_NT: 8
Total 1C: 10072

1D:
    STR_BAL: 663
    VSTR_BAL: 35
    STR_5MIN332: 818
    STR_UNBAL: 252
    HUGE_5MIN332: 38
    HUGE_UNBAL: 6
Total 1D: 1812

Totals:
1C: 10072  # calculated differently than above, as a doublecheck
1D: 1812   # ditto
1M: 5858
1NT: 2028
2NT: 149
2m: 976
20895 (20895) out of 50000  # again, these two counts should match (if they don't, a hand was uncounted/doublecounted)

So, I feel comfortable with my gut-feeling reactions.

• 40%ish of hands are opened (not bad; conservative, but not bad. Note, this doesn't count preempts);
  
• half of them are opened 1♣; 80+% of those are "weak NT or 11-15 4cM or long minor". That's easily within "We call an opening 1 of a minor bid which may be short but isn't necessarily strong a 'grunt'" for me.
  
• 1♦ is strong (but half the strong hands (the ones with a major) have been "grunt"ed out into 1♣). Our strong club defence will work at least adequately against this, especially since we have a call for "both majors" and we are more likely than a normal "strong club" to have a long major (or a fit, for that matter).
  
• 15% are the great calls of 1M and 1NT. Love that, that's why I play Precision.
  
• 2m openers are 2% ish; as pescetom says, that's probably underutilized. Even if you pushed it to 11-15 (and lumped the 5332 11-12s in with the "don't open flat balanced hands", I guess), you'd probably triple that. You still have two ranges (min, max) and invitations still are okay (again, "min, max") if not NT-precise.

Untangling the various options of 1m, even if we don't get into the auction, seems like a daunting task (and I notice it's the part of the system OP *doesn't* present responses or first-round rebids for). But I've played Polish and Swedish Clubs before, I know this kind of thing is resolvable. However, having a "go-to expected hand" when the opponents *do* overcall, like Swedish Club's "weak/kamikaze NT" or Polish's "weak NT. Sure, it might be clubs, but opener often is able to show that later" (or, similarly, Precision 1♦'s "assume the flat hand that can't open 1NT") really helps. This one is more amorphous; I'm sure the OP knows what "to expect", but it's not clear to me yet.

Having said all that, the idea that responder passes 1M unless there's a possibility of game (or a M fit) went out of fashion with the Precision community before 1990. Bidding immediately, rather than beginning to compete only after the opponents have passed information is worth so much more than opener knowing that "the right max should bid game". In fact, I love opening 1M and 90% of the time leaving it in partner's hands to place the contract or ask questions.

I would love to see some results with this system.

For me, there aren't advantages over 21st century Precision (of any stripe, including 0+1♦ and 2m being 11-15, 6m or 5m-4M) that are worth the even more (or maybe it's just new-to-me, not more. But it is new-to-me) difficulty untangling 5- and 6-way minors. Oh, and describing them to the opponents in a 10-second PreAlert.

(and if the OP is JL, who I talked to a lot in Saskatoon, uh, you know, you have in fact solved most of these issues. I still don't have 15 years to work it out like you and P have).

Edit as my response on responses to 1m have been added, I've struck out the parenthetical. I haven't looked at the responses to see how resistant they are to fourth-hand (or even second hand) competition.

[DavidKok]

The system strongly reminds me of a strong diamond structure. The strong diamond systems I'm familiar with have approximately the following system overview:

• 1♣: Catchall, nebulous, by far the most frequent of all the opening bids.
  
• 1♦: Strong, usually 17+ or 16+ or so, nebulous.
  
• 1M: 5(+), limited, usually 11-16 or so.
  
• 1NT: A NT range, either Kamikaze or Strong, with the other hand type opening 1♣.
  
• 2m: 5(+), limited, usually 11-16 or so. Trades with 1♣ to solve problem hands. A common style is to deny a 4cM.

This is very similar to a Precision club with 1♣ and 1♦ swapped and all the ranges filed down a little to adjust for the different amount of bidding space.
All the strong diamond systems I've seen struggle with four problems:

• Using 1♦ as a strong bid is somewhat too high, and the constructive bidding over the strong opening is really very difficult compared to strong club.
  
• The nebulous 1♣ folds like a wet paper bag in competition. It's arguably too overloaded for constructive bidding already, and when the opponents interfere it's a crapshoot. What's more, it contains some of the weakest hands in the system (and is therefore among the most likely to see interference) and is by far the most frequent opening bid (and is therefore the most important part of the bidding system).
  
• The natural 2m openings as I wrote them aren't actually assets, the range is slightly uncomfortably wide (especially of 2♦).
  
• Disclosing which hands are contained in the nebulous 1♣ is difficult, and I've had the unfortunate pleasure of playing against opponents who were sneaking in definitions. But even the people who are up front about this have difficulty with proper disclosure, as there's so many different hand types in there.

Your system takes a lot of the strong hands of 1♦ and the awkward hands of 2m and puts them in 1♣ as well. This helps resolve problems 1+3 but greatly exacerbates numbers 2 and 4. Personally I find problem number 2 to be the biggest issue of strong diamond systems, and I think somewhere between 25% and 50% of all effort on a system like this should go into competitive agreements after we open 1♣. In your system, with the exceptionally high strain on 1♣, probably more.
There's another point about your constructive system over 1♣: normally strong diamond systems 'flip the minors compared to Precision' precisely to allocate more space to their more common opening bid, hoping to gain more resolution using e.g. transfer-based responses or cheap forcing asking bids. Your system over 1♣ has some similarities with standard Precision structures, but I think on the points where it deviates it's a downgrade. I expect that you will respond 1♦ to 1♣ very very often as it contains all weaker-than-game-forcing hands without a 5cM, and now you've used a full round of bidding space to share little information about either hand. This is, again, very vulnerable to interference.

I understand that this is a system you've already put a lot of energy and passion into, and I think it is really nice to develop more unorthodox systems. At the same time I worry about certain design choices, such as 1♣-1♦ being not forcing, 1♣-1M showing a five card suit, all weak hands having to pass your 1M openings, but mostly the lack of competitive agreements. Sorry for being so blunt, but I think this system is unplayable against real opponents - the competitive auctions will cost a lot.

[mikeh]

I strongly agree with David. The annals of bridge bidding theory abound with home-grown methods that work well on paper but don’t work well against opps alive to the inevitable inherent flaws. Designing a system is time consuming….and I can only imagine how many hours the OP put into this. It’s an impressive structure…if one assumes that the opps will remain silent most of the time. I know, from having designed my less elaborate 4 Card major forcing club system with weird two bids some 40 years ago, how invested one can become in one’s ideas, and I commend the OP for his efforts.

I’m not saying don’t play it. I am saying that the OP and his partner need to really work hard on overcoming preemption, which in this case could be as simple as a 1S overcall. Ideally one would want to get close to how Meckwell, in their day, handled interference over their forcing 1C…I read, many years ago, that analysis of their high level matches showed that they did better, on average, after interference than they did without it! And they were VERY good without it.