1. Normally open five-card majors in all seats.

2. Open the higher ranking suit with 5-6 when the hand is minimal, and open the lower ranking suit when the playing strength (not necessarily HCP) justifies an invitational reverse on the next round of bidding.

3. Open the higher ranking of long suits of equal length: 5-5 or 6-6.

4. Normally open 1 with 4-4 in the minors.

5. Normally open 1 with 3-3 in the minors.

6. 1NT = 15-17HCP (NT openings show a balanced hand but can be made with a five-card major or minor suit).

7. 2NT = 20-21HCP

8. 3NT = Gambling solid minor (usually 7-carder) with no outside Ace or King

9. Strong artificial 2 Opener = 22+ HCP with a balanced hand. Unbalanced hands should have approx. 9+ playing tricks with at least 2 defensive tricks outside the long suit.

10. Weak two-bids in diamonds, hearts and spades = 5-11 Points, 6 card suit. A good quality trump suit (2 of the top 3 honours or close to that) is expected in 1st & 2nd seats (as a consequence of playing Feature Ask 2NT). In 3rd seat, the openings can be very undisciplined, especially at favourable vulnerability and at matchpoints.

2/1 GF applies only when our side opens 1 of a suit in 1st or 2nd position, the next player passes, and responder bids a new suit at the 2 level without jumping. Here are all of the cases:

• 1-2
• 1-2
• 1-2
• 1-2
• 1-2
• 1-2

Note:
A first round jump shift is not condsidered a 2/1 response: 2/1 refers to a non-jump bid of a lower ranking suit. Jump shifts retain their normal meaning. By an unpassed hand when RHO passes, a jump shift (as played in SAYC and OKb 2/1) shows a very strong hand and a good 5+card suit, usually a 6+card suit. Furthermore there is nothing special or different about it in OKb 2/1. The availability in OKb 2/1 of the NMF and 4SF conventions results in some auctions in which it is neither useful or necessary to jump shift with 17+ playing points on hands where one might consider it necessary to do so in SAYC due to a lack of good sequences after starting with a 1-level response.

Opener	Opp1	Responder	Opp2	Shows
1	Pass	2!-!-!	any	GF neither player can pass until game is reached, since the 2/1 bid is in a new suit. 1-2 shows 5+cards but 2 of a minor suit is often 4 (or even 3 cards, 3433 pattern), since J2N is used instead of a natural GF 2NT response
1	Pass	2!	3	GF unless opener or responser doubles which would be penalty double. After a 2/1, the opps cannot play undoubled, so passes are forcing if an opp made the last bid, obliging Responder to double for penalty or bid on.
1	2	2-	any	Approx 10+points. Not GF
1	1	2-	any	Approx 10+points. Not GF
1	1	2!	-?-	Weak jump shift - 6+ card suit, 0-6 points. Sign off not GF

Opener	Rebid Shows
X (in comp)	Penalty oriented
Pass (in comp)	Forcing Pass. Responder must X for penalty or bid on
Simple rebid	The catchall bid (a bid that covers all the remaining possibilities), does not promise extra strength or length
Jump rebid	Extra values, 6+card suit, solid or semi-solid depending on agreement. Responder's new suits are cuebids in support.
New suit at the 2-level	Natural, at least four cards, any strength
New suit at the 3 level (not a jump)	Natural, at least 4 cards, extra values (at least a king above min). This bid will be a minor suit. Requiring extra values helps responder gauge whether bidding past 3NT to explore a minor slam in safety. With minimum, bid 2NT if balanced/semi-balanced with stoppers, or rebid your major, the catchall. You may show the suit later if given an opportunity
Jump Shift to 3 level	Ambiguous. Depending on agreement, could be Splinter in support of responder, or a strong 5/5 with most of the strength in the suits. Avoid this bid with new partners
Jump Shift to 4 level	Splinter in support of responder
2NT	12-14 or 18-19 bal, stoppers in unbid suits. With 18-19, make slam try if responder signs off (e.g., natural 4NT after 1-2-2NT-3NT-4NT). Responder will assume 12-14 initially
3NT	15-17 balanced
Single raise of hearts	Any 3-card support, any strength. Not raising denies 3-card heart support. Denies hand appropriate for splinter or jump raise
Single raise of minor	Extra values, prefer 4 card or good 3 card support since responder often has only 4. The extra values help determine whether to bypass 3NT in search of slam. With min, bid catchall or 2NT and maybe show support later.
Jump raise	Most points concentrated in the 2 suits, denies control (A, K, singleton, void) in other suits.

Responder	Rebid Shows
2NT	12-14 or 18-19, stoppers in unbid suit(s). Could be unbalanced if no fit for opener. With 18-19, invite slam if opener signs off in game (1-2-2-2NT-3NT-4NT). Opener assumes 12-14.
Jump to 3NT	15-17, stoppers, could be unbalanced if no fit
Rebid 2/1 suit	Natural, 5/6+cards, forcing
New suit	Natural, 4+cards, or a cuebid if a fit has been established
Raise opener's suit	See section below

1. Since all bids below game are forcing, responder usually has many bids available to raise opener (3+card support if opener's first suit, 4-card support if opener's second suit). The concept of "fast arrival", jumping to game to show less strength than a lower raise, should only apply in situations when opener is usually minimum. This is when opener rebids 2NT or rebids his opening suit, the catchall. Thus:
   1-2-2NT-4 and 1-2-2-4 show a minimum GF hand with 3+ support.
   1-2-2NT-3 and 1-2-2-3 show more than a minimum, and ask opener to cuebid.
   
   
2. "Fast arrival" is not used in other situations, when opener could be any strength, because jumping to game would lose room to make cuebidsIn these other cases, a jump to game in opener's major is a "picture bid", showing points concentrated in the 2/1 suit and the major, and denying any controls (A,K,singleton/void) in the other suits.
   Examples of Picture Bid Sequences:
   1-2-2-4
   1-2-3-4
   1-2-3-4
   1-22-4
   
   
3. If opener has rebid 2 of a new lower ranking suit, responder has 3 raises available for opener's first suit:
   
   
   1. The jump raise to the 3 level is used to show extra values with good cards for a slam (1-2-2-3) and asks opener to cuebid

   2. Splinter - a jump in a new suit showing a singleton/void in that suit, and support for opener's last bid major, examples showing spade support and single/void diamond:
      1-2-2-4!
      1-2-2NT-4!
      1-2-3-4!
      
      
   3. If responder bids the lowest level raise, he just denies a hand appropriate for a Splinter or one of the jump raises.

The auction, 1-(P)-2

This auction is a special case, and is different from auctions that start 1 of a major. The opening bid did not promise 5 cards, and there is no 1NT! forcing available to responder. In many styles of 2/1 this auction is not played as GF. For OKb 2/1 however, the GF is "on". This is consistent with the treatment of 1-2NT as invitational with 11-12 points. The following set of recommended rebids is also consistent with that treatment, but do not expect a new partner to be on the same wavelength, as it is not Universal - accidents can be frequent!

Opener's Rebids after 1-(P)-2

Opener	Rebid Shows
2	5+, any strength, does not deny 4-card major
2NT	12-14,bal,stoppers, does not deny 4-card major
3NT	18-19,bal,stoppers
2-2	4-card major, denies 5+ unless major rebid on 3rd round to show a 5/6 hand. Does not promise extra strength

Note: Since 2 is a GF, what do you do with invitational hands? With a long 6+club suit, bid 1-(P)-3. This shows 10-12 points and is invitational, but non-forcing. It is no long a strong jump shift. With no long club suit, no 4-card major, and a hand that can't make an inverted raise of diamonds, bid 2NT, which shows 11-12 points. You will have to do ths on some hands that don't have stoppers in one or both major suits.

As a result of the 2/1 response being a "Game Force", responder will often have a 10-12 point hand with which he would like to make a 2/1 bid but cannot; hence the 1NT! Forcing convention. The 1NT! response to 1 or 1 shows 6-12 and is a one-round force. The 1NT! response denies a hand appropriate for a single raise or limit raise and, usually, over a 1 opener, denies 4 spades

Example hand types where the 1NT! forcing bid can be used systemically or tactically:

1. A hand with exactly 3 trumps and 10-12 support points that plans to jump in opener's suit over any rebid by opener.
2. Some players respond 1NT! with 3 card support and a poor 6-7 points in support in order not to overly encourage partner.
3. A hand with more than 2 card support but very weak approx 4-6 points, to discourage the opps from entering the auction.
4. Over an opener of 1, 1NT! usually denies 4+ spades, but is correct with a hand type of approx 5-9HCP, a weak 4 card spade suit, and a good 6+ card minor suit.
5. Some players respond 1NT! with a balanced hand that has more than 12HCP. This occurs most often with 13-15HCP and relatively weak holdings in the 4 card suit(s).

Sequence	Opener holds:	Opener's Rebid	Shows
1-1NT!	KQJT9 KJT6 A3 54	2	4+,appx 12-18 points,NF
1-1NT!	KQJT9 KJT A63 54	2!	3+,appx 12-18 points,less than 4 hearts,fewer clubs than diamonds,NF
1-1NT!	AQJT KJT98 Q6 54	2!	2+,appx 12-18 points, may have 4 spades, clubs equal or longer than diamonds.(the example hand is not strong enough to reverse).NF
1-1NT!	KT7654 AK3 6 AQ4	2!	2+, appx 12-18 points, less than 4 hearts, clubs equal or longer than diamonds:(in this example the spade quality is not good enough for a rebid.Opener hopes for another chance to clarify).NF

Sequence	Responder	Shows
1-1NT!-2	pass	6-9HCP
	raise	10-12 support points, 2 or 3 trumps, NF
	2NT	10-12HCP, less than 3 trumps,does not promise NT shape or stops, NF
	3xnew suit	10-12 points, v good 6+card suit, Invite
	raise to 4	10-12HCP, 3 of opener's major, NF
1-1NT!-2	pass	6-9HCP, usually 5+ in opener's minor, less than 2 of opener's major
	raise major	6-10HCP, usually 2 of opener's major,3 only if v weak, NF
	2x new suit	6-9HCP, usually 6+(or 5 good) in bid suit, less than 2 spades unless good new suit, NF
	2NT	10-12HCP,fewer than 3 trumps,does not promise NT shape or stops,NF
	jump shift	10-12 points, very good 6+ card suit, NF
	jump raise major	10-12 points, exactly 3 trumps
	raise minor	10-12 points, usually 5+ trumps
	4 of major	13+ points: a hand that increased in value after opener's rebid (includes 1-1NT!-2-4)

1. Jump Shift by Opener (example: 1-1NT!-3). Responder usually prefers back to opener's major with 2 card support (or bids 3NT with stoppers), even when holding good 4 card support in the minor. This is to conserve bidding space and allow for the likelihood that opener's second suit is short. With 3 card support in the major and 10-12 support, responder follows through on the original plan and jumps to game in the major.
2. 1-1NT!-2/-2: logically, this cannot be natural. A common agreement is for this to be an artificial raise of opener's second suit, showing 4+ support and invitational values. By extension, a raise of opener's minor changes in meaning to be 5+ card support and less than invitational. This approach can shut out the opponents and occasionally leads to thin shapely games or slams.
3. Partner opens 1, you respond 1NT!. Now partner rebids 2 or 2. You bid 3, which is TO PLAY. This is one exception to the normal rule where typically a new suit by responder is forcing. Here it is not. However, with say, Axxxx AQxx x Axx, another call by opener would be warranted since he has three-card support for responder's minor, a singleton in an unbid suit and both aces in the long suits.

Sequence	Responder holds:	Rebid	Shows
1-1NT!-2!	K43 98 KJ43 J432	2	Correct to 2. Don't pass
	K43 K98 AJ J9854	3	10-12 points.Exactly 3x,does not deny 4+.Invite
	T43 K8 QJ2 KQ876	3	10-12 Points 5+,denies 3x.Invite
	K43 A8 QJ32 T98	2NT	10-12 Points, gd stops in the unbid.Invite
	6 A53 52 AQT876	4	10-12 Points, 3x (hand has added value with dbl-fit).

A jump shift by responder in competition e.g., 1-1-2!, shows a 6-card suit and 0-6 points

2NT Response to Weak 2 Opener ( ! )

A 2NT! response over an opening Weak 2 is forcing and shows game interest (even if the opps intervene). Opener should show a "feature": ie. a suit with Ace or King. Rebid 3NT with AKQ in the opening suit. With no feature, rebid 3 of the suit.

Raise Only Non-Forcing (R-O-N-F)

A method of responding to weak 2 openers which utilises both 2NT! for feature, and a new suit as forcing response: hence, the raise of partner's suit is the only non-forcing response below game.

Unusual NT( ! )

1. A jump overcall of 2NT! over a 1 of a suit opener is Unusual NT and shows at least 5/5 in the lower 2 unbid suits. Overcaller's values can be very wide ranging, but should be concentrated in the long suits.
2. After a strong 2 opener, an overcall of 2NT! has the same meaning.

Note 1: Except 3NT, any other NT bid after both opponents have bid and partner has passed can also be considered as Unusual NT
Note 2: A 4NT bid over opp's opener of 1 of a suit should also be recognised as Unusual NT

Michaels Cuebid ( ! )

The Michaels Cuebid promises a 2-suited hand.

Opp1	O/Call	Overcall Shows
1-	2-!	both majors
1	2!	spades and an undisclosed minor
1	2!	hearts and an undisclosed minor

Note 1: A response of 2NT over the major suit cuebid asks partner to bid his minor
Note 2: In a competitive auction, if 2NT is unavailable, responder can bid 4 (non-forcing) or 4NT (forcing) to locate the minor. 3NT is always to play.
Note 3: The strength of the Michaels Cuebid follows the same guidelines as used for Unusual NT overcall. It is more "shape" than HCP that counts

Jacoby Transfers to Majors ( ! )

Jacoby transfers (Xfers) show a five+ card major suit:

2 is a transfer to 2
2 is a transfer to 2

Opener	Responder	Shows
1NT 2	2! Pass	Responder has 0-7HCP with 5+hearts
1NT 3	2! - ? -	Opener has 16+ support points and 4 hearts (invitational)
1NT 3	2! - ? -	Opener has 16+ support points,good club suit and 4 hearts (forcing)
1NT 2	2! 2NT/3	Responder has 8-9 HCP (invitational to 3N or 4)
1NT 2	2! 3-	Responder has 9+HCP, good side suit, but may not be long (GF, poss slam interest)
1NT 2	2! 3NT	Responder has 9+HCP asks Opener to pass or bid 4

Note 1: Jacoby Transfers are also used over openers of 2NT
Note 2: Jacoby Transfers are "off" altogether if the NT opening is overcalled.

Texas Transfers ( ! )

Jump responses of 4/4 over opener of 1NT/2NT to transfer to 4/4 when responder wants to be in game but has no slam interest

Opener	Responder	Opener
1NT/2NT	4!	4
	4!	4

The idea behind this convention is similar to that behind Jacoby Transfers - it is better for opener to be declarer, since his high cards won't be exposed to the defenders.

Using both transfer conventions, responding to both 1NT and 2NT, Root/Pavlicek recommend the following understandings:

1. Texas, then pass is signoff in game, therefore:
2. Jacoby, then raise to game is mild slam try (not forcing but opener is invited to bid again with maximum).
3. Jacoby, then 4NT is defined as quantitative slam invitation, therefore:
4. Texas, then 4NT is Blackwood.

Opener	Responder	Opener	Responder	Using both JXfer and Texas, Shows
1NT	2-!	2-	4-	Suggests slam interest
	2-!	2-	4NT	Quantitative slam invitation
	4-!	4-	Pass	Signoff in game, no slam interest
	4-!	4-	4NT	Blackwood, not quantitative

Texas Transfers are "on" in competition through 3 (see OKb 2/1 CC says "on /x"), i.e.,

Opener	Opp1	Responder	Shows
1NT	2-3	4!	Xfer to 4
	2	4!	Xfer to 4
	3	4	Natural, not an Xfer

Minor-Suit Stayman is just what its name implies: a device that allows a partnership to look for a minor-suit fit after an opening bid of 1NT (and over 2NT/3NT see note 2 below). Presupposing the use of Jacoby Transfers, the 2 response to 1NT is no longer needed to show spades and can be used to ask opener to bid a 4-card minor suit. The OKB 2/1 card uses a specific variant of MSS, which also includes weak hands with a long diamond suit, hence the notation “MSS or correct to or 3 with diamond bust”. This is a treatment that is part of the Walsh system. Other MSS variants may not include the weak hands that Walsh does, and have different response structures, so it may be best to avoid this bid in a new partnership.

2! response to 1NT(strong NT) shows one of three types of hands. It is either a weak hand with long (6+) diamonds,a weak hand with both minors (5-5), or a strong hand at least 5-4 or 4-5 minors with slam interest.(With both minors and only minimum values for game, bid 3NT. 9 tricks in NT is usually easier than 11 in a minor. Using MSS may pinpoint a weak major for the opponents to lead)

The 1NT opener should rebid:

1. 2NT = denies a 4 card or longer minor
2. 3 or 3 = at least 4 cards in the minor bid, bid the better one with both.

After using MSS and hearing any of the above rebids, responder's available rebids are:

1. 3! over 2NT = weak both minors, opener may pass or correct to 3 (e.g. xx x KJxxx QTxxx)
2. 3! over 2NT/3 = weak with long diamonds (x xx QJxxxxx Qxx
3. Pass over 3/ = content with contract, weak hand
4. 3NT = 2245 or 2254, slam invitational, non-forcing (xx Ax AKxxx KJxx)
5. Any major suit bid (!) = single/void in that suit, slam interest (3! with x Ax AKxxx KJxxx)
6. 4NT = Roman Key Card Blackwood if minor suit has been agreed but natural otherwise

Note 1: Minor-Suit Stayman (like Jacoby Transfers) is "off" altogether if the NT opening is overcalled. If the 2! response is overcalled or doubled, opener may:

1. pass with nothing else to say
2. double or redouble for penalty
3. make his normal bid

Interference after the 2! bid does not affect the MSS bidder.

Note 2: The use of MSS over 2NT, or 2-2-(2NT/3NT) is easily defined in that, if Jacoby applies, so does MSS, ie ., if a diamond or heart bid is Jacoby, then a spade bid is MSS. The use of MSS over 2/3NT always shows slam interest. If a minor suit has been agreed, then a later bid of 4NT is RKC, otherwise natural.

2nt->3 = club signoff, or 4441 (!)

Over opener's 1NT, a direct response of 2NT! is a puppet(relay) to 3! which responder can pass with clubs and a bust, or show a game forcing 3-suited hand, either 4441 or 4450 with a 5 card minor. With the strong hand rebid the suit containing your singleton/void. With short clubs, either rebid 3NT, non-forcing, or bid 4! with slam interest to force opener to bid.

Examples: after 1NT-2NT!-3!-?

1. Pass (x xxx Kxx QT9xxxx)
2. 3! ( AJxx x AKxx Qxxx)
3. 3NT! (AJxx AKxx Qxxx x)
4. 4! (AJxx AKxx AQxx x)

After the strong shortness showing bids, opener picks a suit or rebids in NT with the short suit well-stopped (and hence wasted values for a suit slam).  Over suit agreement, 4NT is RKC. Over 3NT, 4NT by responder is natural and invitational.

When playing a direct 2NT to 1NT as artificial, one must start with 2 Stayman to invite game in NT.

1. Opener with both hearts and spades bids 2
2. The sequence 1NT-2-2-2 shows exactly 4 spades and is invitational to game. Opener may pass, bid 2NT, 3NT, or 4
3. The sequence 1NT-2-2-2N! is invitational to game and denies 4 spades
4. Other sequences that start 1NT-2-2any-2N! do not promise or deny a 4 card major. This should be explained at the time of the 2NT rebid.

3 level responses to 1NT

The OKB 2/1 CC does not specify what the 3 level responses to 1NT should mean. When playing the above gadgets it is right to assume that the sequences 1NT-3 and 1NT-3 are natural non-forcing NT game invites showing 6+ cards with 2 of the top 3 honors and very little on the side (not AKxxxx since opener can duck one round and usually run another 5 tricks; with this holding bid 2NT or 3NT).

The 3 level major suit bids should be avoided without discussion.

When responder is an unpassed hand and rebids the 4th suit in an uncontested auction, it is game forcing and artificial.(eg. 1-P-1-P-1-P-2!-?). Responder is using the 4th suit to indicate a good hand with 12+ points and no attractive rebid. Opener should respond with a natural bid that further describes his hand. Taking the above bidding sequence as an example, opener should rebid as follows:

Opener's Rebid	Shows
2-	Rebid of own 1st/2nd suit at cheapest level, natural, waiting, does not deny extra values
2	Raise partner's 1st suit with 3-card support (Jump raise with more than minimum)
2NT	Bid NT to show stop in the 4th suit and 12-14 or 18-19 points (bid 3N with 15-17 poss unbalanced)
3	Raise 4th suit with 4+ of them
3	Jump rebid of opening suit showing extra length and strength

4SF does not apply in the following situations:

1. In an "up the line" bidding sequence, e.g., 1--1-1. This is not artificial and forcing only for 1 round.
2. When responder's rebid is a jump bid in the 4th suit showing invitational values and at least 5/5 in his bid suits, e.g., 1-1-2-3
3. In competition

With a solid minor of 7 or more cards, open 3NT! (The hand should have no outside Ace or King). If responder has stops in the other 3 suits and no minor void (and no slam interest), he can pass. If he does not have the required stops and entry, he must bid 4 which opener can adjust to 4 if necessary.

Note: The official OKbridge 2/1 summary states that the 3NT bidder should not have a void or small singleton. However, there are almost no hands that meet the requirement and few players who practice it.

Negative Doubles (also known as Sputnik) ( ! )

A negative double shows competitive or better values with no clear bid after partner has opened 1 of a suit and RHO has overcalled in a suit. The double shows about 6+ hcp at the 1-level and about 2 more hcp for each higher level. In OKbridge 2/1, the negative double applies when the overcall is 3 or lower.

The most frequent use of the double is to show a 4 card holding in one or more unbid major suits at any level. However, a negative double also is correct with 5 or more cards in a major when the hand is not strong enough to bid the suit directly. For instance, a new suit at the 2 level shows about 11+ hcp, and at the 3 level or higher is game forcing.

Pard 1	Opp 1	Pard 2	Pard 2 Shows
1	1	X!	6+HCP and 4x . A bid of 1 promises 5
1	1	X!	6+ support points and 4x or 5-10 Points + 5x
1	1	X!	6+ support points and 4/4+ in the majors
1	1	X!	4/4+ in the minors

Note:

1. A direct double of opponent's 1NT opener is penalty oriented.

2. On OKbridge, always include a brief message to the opps when making a negative double: e.g., "=negx" or "=neg". Negative doubles are not alertable in ACBL competition, but are in most other areas.

Note 1: All rebids by the Neg Xer below game are non-forcing, except a cuebid of opps suit.
Note 2: Using Neg Xes means that partner is unable to double for penalty. Therefore, when an opp's suit overcall is followed by 2 passes, opener should try to re-open with a double, if he has 2 or less cards in the opp's suit, since partner may have passed with a good hand for penalties.

Responsive Double ( ! )

The responsive double is a response to partner's takeout double after the opponents have bid and raised a suit. For example: 1 - X - 2 - X! The responsive double is based on the principle that a penalty double is usually unrewarding, therefore the responsive double shows scattered values with at least 6 points and interest in locating a fit. If the opponents are bidding a minor suit, a responsive double asks partner to pick a major suit. If the opponents are bidding a major suit, a responsive double requests partner to choose a minor suit. For instance, advancer might hold KT43 QJ32 93 JT9 and hear: 1 - X - 2 - ?, he should make a responsive double to ask partner to bid a major.

Note: A double by advancer is responsive only when the opponents have opened a one-bid and raised it. Some players also use the responsive double when partner has made a simple overcall in a suit. In this case the responsive double would show 8+HCP, little support for partner's suit, and usually 5/5 or better in the 2 unbid suits: e.g., 1-1-2-X! would suggest 5/5 hearts/diamonds: partner with 3 card or better support for either should bid that suit rather than repeat his own if it is only a 5 carder. With no support for either he will rebid his own suit.

The above description is fine if you have such "perfect" hand types. In practice, however, many players make a responsive double with any hand that has competitive or better values and no other good bid. For example:

1. You hold Kxx KQx xxx Axx and you hear 1-X-2, you have no good call so must use the responsive double and await partner.
2. You hold Kx Axx xxxx Jxxx and you hear 1-X-2, again, you have no good call so must use the responsive double.
3. You hold Txxx KQx xxx Jxx and you hear 1-X-3. Here again, with no good call, you must use the responsive double

A good rule of thumb is not to use an ambiguous bid or sequence when there is a clear specific bid or sequence available

Bidding situations in which double is NOT responsive but for penalty:

1. RHO has bid a new suit, e.g.,1 - X - 1 - X
2. Partner has made a jump overcall, e.g., 1 - 2 - 3 - X
3. LHO has opened with a preempt, e.g., 2 - X - 3 - X
4. Partner has overcalled in no-trumps, e.g., 1 - 1NT - 2 - X

Note: On the OKb 2/1 cc, responsive doubles are on through 3.

Support Doubles and Redoubles ( ! )

You open 1 and hear LHO pass. Partner responds 1 (promising a four-card suit), and RHO butts in with 2. Now what? Users of the support double are happy in this situation; they simply double! to show a three-card spade raise. This lets them bid 2 to show a four-card raise. When the opponents bid and raise a suit, support doubles are also on: they also apply when RHO makes a takeout double

Opener	Opp1	Responder	Opp2	Opener's Rebid Shows
1	1	1	2	Opening values and 3xspades
X!	-?-
1	1	1	2	Opening values and 4xspades
2	-?-
1	Pass	1	X	Opening values and 3xspades
XX!	-?-
1	Pass	1	X	Opening values and 4xspades
2	-?-

Note: On the OKb 2/1 cc, support doubles and redoubles are on through 2

Jacoby 2NT (J2N) ( ! )

If responder jumps to 2NT over a 1/1 opener, it is J2N asking opener to show a singleton or void. It shows 13+ support points, 4+ in opener's suit and is game forcing. Opener rebids as follows:

Opener	Responder	Opener	Opener Shows	Responder
1	2NT!	3!	Max hand, 18+Points and strong suit but denies short suit	Either sign off in game or look for slam
		3/3/3!	Singleton or void in bid suit
		3NT!	Medium hand, 15-17 Points, denies short suit (artificial)
		4	Minimum hand and denies short suit
		4/4/4	Strong 5-card side suit

Splinter Bids ( ! )

The use of an unusual jump bid to show a singleton or void in the suit bid and excellent trump support for partner's last bid suit. This is forcing to game and unlimited.

North	South	Shows
1	3!	13+ support points, agrees hearts, singleton or void spade (forcing).
1/1	4/4!	As above but with club/diamond void/singleton
1	4!	As above but with heart void/singleton

Note:

1. In competition after opponent's t/oX, splinter bids are still "on"
2. In non-competitive auctions, splinter bids may be extended to areas of rebidding, by both opener and responder. In this respect the "rule of thumb" is if a particular new-suit bid would be forcing, then one level higher in that same suit is a splinter bid.
3. Some partners do not like splinters with a singleton A or K.
4. Some partners do not like splinters with a void.
5. Some partners use 1-4 as a splinter. This might seem to be unnecessary when 1-2 is game forcing, thus leaving 1-3 as the unusual jump.
6. A splinter usually cannot be used to show shortness in partner's first bid suit.

2nd Negative - Response over Strong 2 Club Opener

After a negative 2 ("may be waiting") response to a strong 2 opener, it is necessary to expand on those auctions where opener rebids in a suit, since responder is required to bid again even with a bust. To solve his dilemma, the 2nd negative is used: i.e., the cheapest 3 of a minor rebid (if available or 3NT if not), is the 2nd negative: this bid is artificial and shows about 0-4 HCP, but never an Ace. The main advantage of the 2nd negative is obtained when it is not used, making any other rebid by responder constructive, showing useful values. (note: see errors in the OKb 2/1 CC which says 2nd neg is "cheapest 3 level")

Jordan 2NT (Truscott 2NT) ( ! )

1. Over 1 of a Major opening

When opener's 1 of a major opener is doubled for takeout, 2NT! by responder is used to indicate a "limit or better raise" of opener's suit, approx 9-12 points and 4/(3 gd) trumps, forcing to at least 3 of opener's major; this leaves a "jump raise" as preemptive showing 0-8 points (possibly 6-8 if vul) with 4+ trumps, e.g., 1-X-3

After the 2NT! call, opener may

1. signoff in 3 or 4 of his major
2. bid a new suit to try for game or slam., e.g., 1-X-2NT!-3 would be a game try and forcing.