A reverse is a non jump bid in a suit that forces partner to take a preference to the first suit at a high level.

The most common example is opener's rebid is higher ranking than his first suit, e.g., 1C-1S; 2H. In that example if responder wants to take a preference to the first suit, she will have to bid at a higher level (3C). Another example of a reverse occurs when opener's rebid is lower ranking than his first suit, but at the three level, e.g., 1S-2H; 3C. This second type of reverse is called a high level reverse. Finally, responder can also reverse, e.g., 1C-1H; 2C-2S.

Because reverses force partner's preference to a high level, they show extras and are forcing. In Standard American, a reverse by opener shows 16+ hcp and is forcing for at least one round. (Some play a reverse as about 18+ hcp and forcing to game.) Responder's reverse is typically played as game-forcing.

• Structured reverses
• 2NT puppet/relay
• DeSerpa structure
• Relays

After a reverse, the main problem occurs when responder has a weak hand (less than 10 in Root-Pavlicek's definition). It's assumed the partnership will know what to do if responder has a stronger hand... (A) and (B) describe methods for responder to show weakness.

A) After responder has bid a major

In this case, responder shows weakness by
   i) rebidding the major, to show at least a five card suit
   ii) bidding NT to show a four card suit.

1C - 1H 2D - 2H	2H is weak, 5+ hearts
1C - 1H 2D - 2N	2N is weak, only four spades

B) Responder has bid NT (6-10 over a minor or 6-12 over a major)

In this case, responder shows weakness (bottom half of range) by
   i) showing preference to the lower suit
   ii) bidding NT to deny support for the lower suit

1D - 1N 2S - 3D	3D is weak, does not guarantee three card support
1H - 1N 2S - 2N	2N is weak, at best Jx in hearts

GAME FORCING REBIDS BY OPENER after a weakness signal

1) Bidding the 4th suit (always forcing). If a minor, it shows 5-4-4-0 distribution. If a major, it must be artificial.

1C - 1S 2H - 2S 3D	3D shows 0-4-4-5, forcing
1C - 1H 2D - 2N 3S	3S is artificial, forcing

2) Show support to a four card suit.

1C - 1S 2H - 2N 3S

3S shows support with a strong hand. Some play this as three card support, others as four.

3) Bidding the higher suit again to show at least 6-5.

1D - 1S 2H - 2N 3H	3H shows five hearts, six diamonds, forcing
1D - 1N 2S - 3D 3S	3S shows five spades, six diamonds, game-forcing

4) Jump in the lower suit to show extreme distribution (7-4).

1C - 1N 2S - 2N 4C

4C shows four spades, seven clubs, forcing

NON-FORCING REBIDS BY OPENER

1) Raise of partner's suit (if 5 carder).

1D - 1S 2H - 2S 3S

3S invitational

2) Bid 3NT (to play).

1D - 1S 2H - 2S 3N

3N to play

3) Raise of partner's weak raise.

1D - 1N 2H - 2D 4D

4D invitational

4) Bid 2NT to show 4th suit.

1D - 1S 2H - 2S 2N

2N shows a club stopper

After a reverse, the 2NT bid is used artificially to show weakness. Responder may pass opener's nonforcing rebids, or take a simple preference to one of opener's suits.

Some play 2NT as a puppet to 3C; others play it as a puppet to the lower ranking suit. Opener rebids the forced suit without extras.

After a reverse (e.g., 1C-1S; 2D) there are two direct forcing raises for responder (3C and 3D) and three conventional bids (2H, 2S, and 2N). The conventional bids are used to show a weak hand, a five card suit and a strong fit for one of opener's suits, respectively. In steps, the conventional bids are:

Step	Meaning
1st	Nonforcing, weak hand
2nd	Forcing, asks for three card support
3rd	Forcing, strong fit

By strong fit, that means three certain cover cards or two cover cards and two potential cover cards. Certain over cards will cover losers in partner's long suits; potential cover cards are kings and queens that may cover losers in side suits. The direct raises of opener's suits deny enough strength for the conventional raise.

Opener rebids naturally showing three card support, side fragments (the fourth suit is thus a splinter) or rebids 3NT (5422 shape). Responder then rebids to show the number of fillers (certain cover cards). These rebids begin with 4C.

Over the "weak" direct raises, the meanings are:

Bid	Meaning
4C	1 filler, 2 potential side cover cards
4D	2 filler, 1 potential side cover card
4H	0 filler, 3 potential side cover cards
4S	3 filler, 0 potential side cover cards

DeSerpa assumes that opener will have at least three honors in their own two suits, so responder will not have more than three fillers. Opener should be able to know what cards responder has with the last two responses. Opener can relay over the first two responses to ask responder to show the side cover cards.

Over the strong conventional raise, the meanings are:

Bid	Meaning
4C	0 or 3 fillers
4D	1 or 4 fillers
4H	2 fillers

These methods occur after responder has bid a suit and opener has reversed. After opener's reverse, responder agrees
   i) to the first suit by either bidding the fourth suit or making a preference to it (this requests natural bidding)
   ii) to the second suit by raising it.

Numerical relays are used after the reverse. That means the suit lengths are "numerically coded" with the responses to the relay shown in ascending order based on the number. Responder's cheapest rebid continues the relay, although 3N and game bids in the agreed suit stop the relay. After the start of the relay, opener's rebids show (in order):
   i) Total distribution
   ii) Number of keycards
   iii) Suit honors (via a spiral scan)

Opener's first rebid shows distribution. The first two main suits are shown first. Responder's suit is shown third. Note that with 5440 distribution, opener is expected to splinter in support or not reverse at all.

Step	Two main suits	Responder's suit	Fourth suit
1st	5-4	1	3
2nd	5-4	2	2
3rd	5-4	3	1
4th	6-4	1	2
5th	6-4	2	1
6th	6-4	3	0
7th	6-4	0	3

After distribution is shown, opener shows keycards in steps (0 or 3, 1 or 4, 2 without the queen and finally 2 with the queen), then spirals in the main and side suits. If opener's long suit is clubs, the second suit is diamonds, and responder's suit is spades, and responder has agreed diamonds as the keycard suit, then the spiral of suit honors goes:
     diamond queen (if not shown)
     club king
     spade king
     heart king
     club queen
     spade queen
     heart queen
     diamond jack (trump suit)
     club jack, etc

For the above example, the first step denies the diamond queen. The second step shows the diamond queen, but denies the club king. The third step shows the diamond queen and club king, but denies the heart king. And so on.

Here is a full example.

Bid	Meaning
1C - 1S 2D - 2H 3C - 3D 3S - 4C 4S - 6D	2H agrees diamonds, starts relay 3C shows exactly 3-1-4-5 distribution, 3D relays 3S shows 1 or 4 keycards (diamonds key), 4C (not 3N) relays 4S shows queen of trump (D), king of clubs, denies king of spades