Bridge Sense

STRONG CLUB

Precision Club.

One decision shapes the entire system: every hand of 16 or more opens 1♣. Everything else follows from what that makes possible: if the strong hands are all somewhere else, every other opening can promise a narrow range, and partner can start judging the contract immediately.

The version taught here is the Precision played today: natural, game-forcing positive responses, a simple values scheme when the opponents interfere, and standard preempts away from the strong club. Every convention the engine plays is documented on this page, and the engine grades against exactly what is written here.

THE PREMISE

Limited openings, and what they buy

In a natural system, partner opens 1♠ and you know they hold somewhere between 11 and 21. Narrowing that takes two more rounds of bidding, and until it happens you cannot tell whether your 12 points are worth a partscore or a game.

Precision closes that window on the first call. Because 1♣ has taken every hand from 16 up, an opening of 1♠ promises 11-15: and responder can add their own count to a five-point range instead of a ten-point one. Much of what looks like judgement in a natural auction becomes arithmetic here.

THE STRUCTURE

Opening bids

1♣16+ HCP, artificial and forcing. Says nothing at all about clubs. Every strong hand starts here regardless of shape: that's what frees every other opening to be narrow.
1♦11-15, the catch-all. What's left when a hand has no five-card major, no long club suit, and isn't a 13-15 balanced. It is not a diamond suit and can be short: never raise it as though it were.
1♥ / 1♠11-15 with a five-card suit. Limited on the very first call, which is the whole point: partner can judge the final contract now instead of two rounds later.
1NT13-15 balanced. Lower than a natural system's 15-17 because everything from 16 up has already gone to 1♣.
2♣11-15 with a long club suit, natural, not strong. Six clubs, or five alongside a four-card major or a diamond shortage: hands the 1♦ catch-all describes badly.
2♦11-15, both majors, at most one diamond. A shape the 1♦ catch-all handles badly, so it gets its own bid.
2♥ / 2♠Weak two: 5-10 with a good six-card major. Unchanged from a natural system, Precision alters the strong and limited openings, not the preemptive ones.
2NT22-24 balanced. The one strong hand that does not go through 1♣: it is already describable in a single bid.
3-levelA seven- or eight-card suit below opening strength: a standard preempt, same as every other system here.
4♣ / 4♦ (Namyats)A strong four-level major, transferred: 4♣ shows solid hearts, 4♦ solid spades - 7.5 to 8.5 playing tricks with an outside control. The step relay asks; the direct major signs off.
4♥ / 4♠Purely preemptive: an eight-card suit well short of opening values. The strong version opens the minor below (Namyats).

THE ENGINE ROOM

The strong 1♣

Why gather every strong handOne artificial bid absorbs everything from 16 up. Because those hands are elsewhere, every other opening can promise 11-15: a five-point window rather than the ten-point one a natural 1♠ carries.
It is forcingPartner may not pass, however weak. That's what makes the 0-7 negative response necessary and safe.
It says nothing about shapeThe cost of the method. Opener describes their distribution on the second round, having spent the first round only announcing strength.

ANSWERING

Responding to 1♣

1♦, negative0-7. Artificial; nothing to do with diamonds. Its job is to say "no game here" before the auction climbs any further.
1♥ / 1♠, positive8+ with a five-card major. Game-forcing: 8 opposite 16 is 24 already, so the partnership can explore slowly with no fear of being dropped.
1NT, positive8-10 balanced with no five-card major.
2♣ / 2♦, positive8+ with a five-card minor. Game-forcing, like every positive.
2NT, positive11+ balanced with no five-card suit to name. Opposite 16+ this is slam territory, and 2NT says so while leaving room to find out where.
A four-card suit8+ with 4-4-4-1 shape: no five-card suit, not balanced, but the positive still has to be made. Bid the longest suit available and describe the shape on the next round.

The negative is the response you will make most often, and it is worth making cheerfully. Telling partner immediately that there is no game saves the auction from climbing on a hand that cannot support it.

ROUND TWO

Opener’s rebid after 1♣

1♣ announced strength and nothing else, so the second call is where opener finally describes the hand. Opposite a negative the balanced rebids carry the range in three steps; opposite a positive the partnership is already in game territory and the job is to choose between the fits rather than to establish whether one exists.

1NT16-18 balanced. Partner has at most 7, so game is unlikely and the hand belongs at the one level: the strong club has already done its job by finding that out cheaply.
2NT19-21 balanced. Invitational rather than forcing: partner with 6 or 7 can still bid game, and with nothing at all they pass.
3NT22 or more balanced. Even opposite a negative that is enough to insist on game.
A suitA five-card suit with 16 or more. This is where the shape finally arrives, 1♣ said nothing about distribution, and the second call is when opener starts paying that back.
Raising a positivePartner promised 8 or more and you have support. 8 opposite 16 is already game, so there is nothing to investigate below it: raise to the level the fit is worth.
3NT over a positiveThe partnership is in game territory the moment a positive appears, 8 opposite 16 is 24 at worst. With no fit worth naming, take the notrump game.

WHEN THEY BID

Interference over 1♣

The opponents' best weapon against a strong club is to bid over it (cheaply, and often on very little) because 1♣ is the one bid the system cannot afford to have crowded. The modern answer is deliberately simple: three bands of values, and every free bid natural. Pass is the bottom, double is the in-between hand, and anything responder chooses to bid is real and forces to game.

Pass0-4. Uncontested this hand had to bid 1♦; their overcall lets silence carry the same message. Partner still has 16+ and another call coming.
Double5-8, the values card. Real values, no bid that describes them yet: opener places the contract knowing the range within three points.
1♥ / 1♠8+ with a five-card major, bid at the one level exactly as if they had stayed silent. A major fit is the one thing worth bidding before anything else.
A new suit8+ with a good five-card suit, natural and forcing to game. From 9 up, a hand with no five-card suit and no stopper for notrump names its longest four-card suit instead.
1NT / 2NT8+ balanced with their suit stopped, cheapest available, forcing to game.
2♥ / 2♠A six-card major with two top honours and 3-7 points. Weak, deliberately: it takes their room and values the hand in one call.

When they double 1♣

Their double is a lead director, not a penalty threat, and it hands you an extra call: pass now exists, and redouble takes over as the values card. Everything from 8 up is bid exactly as if they had stayed silent.

Pass0-4. Their double hands you the negative for free: uncontested this hand had to bid 1♦.
Redouble5-7, the values card. Enough to announce the balance of strength, not enough for a game-forcing free bid.
1NT8+ balanced, forcing to game. The double of an artificial club took nothing away, so the positive is bid naturally.
A suit8+, natural and forcing to game: a five-card suit, or the longest four in an unbalanced hand without one.

Schemes vary: some partnerships play transfers over interference, others still count controls in the older style. This page documents the treatment the engine bids and grades against.

THE DETAILS

House treatments

Most of this system is the Precision anyone plays. These are the agreements worth writing down because partnerships genuinely differ on them.

Responding to 2NTTwo points higher than a natural 2NT opening, so every threshold drops: 3♣ is Stayman on 3+ with a four-card major, 3NT is the game bid on as little as 3, 4NT invites 6NT quantitatively on 9-10, and 6NT is bid outright on 11+, eleven opposite a minimum twenty-two is thirty-three. Only 0-2 passes.
1NT opening13-15, never with both four-card majors, and 14-15 at unfavourable vulnerability where a doubled 1NT is the cheapest disaster available to them.
2♦ opening11-15, short in diamonds: 4-4-1-4, 4-4-0-5 or (3-4)-1-5.
1♣–2♥ / 2♠4-7 with a six or seven card major headed by two honours, but not ace-king. A weak jump in answer to a strong club: partner has the strength, you have the shape.

THE RESIDUE

The 1♦ catch-all

What it promises11-15 and nothing else. It's the residue after the specific openings have taken what they describe, which is why it can be short.
How responder treats itLook for a major first. A four-card major with 8+ is worth bidding at the one level, because 1♦ has told you almost nothing and the major fit is what's most likely to be missed.
The trapRaising diamonds. Opener may hold two, or fewer. Support requires real length, not the three cards that would be plenty opposite a natural 1♦.

Answering it

Every response here is shaped by one fact: the diamonds may not be there. That moves the raise up to a five-card requirement and puts finding a major ahead of everything else.

1♥ / 1♠A four-card major with 8 or more, forcing for one round. 1♦ was a catch-all rather than a real suit, so finding a major fit is the first job before the auction settles anywhere else.
1NT6-10 balanced with no major worth showing. There is no fit to look for, so describe the hand and let a partner capped at 15 decide whether there is more.
2♦6-10 with five or more diamonds. Note the five: partner may hold as few as two, so the three cards that would be a routine raise of a natural 1♦ are not enough here.
3♦11 or more with five or more diamonds. Jumping shows the values and the length together, and asks whether 3NT is on.
3NT16 or more balanced. No fit to find and no long suit to develop, so take the nine tricks you can count. Slam needs partner at the very top of a narrow range plus a source of tricks neither of you has shown.
PassUnder 6. Opener has at most 15, so there is no game and nothing to gain by keeping the auction alive.

THE DIVIDEND

Responding to 1♥ / 1♠

This is where a limited system pays for itself. Opener has promised five cards and 11-15, so responder is not describing a hand and waiting to hear more: they are adding two known quantities and placing the contract on the first call.

2♥ / 2♠6-10 with three-card support. Opposite a limited opening this is where the hand belongs: there is no hidden 19-count waiting to make game.
3♥ / 3♠11-12 with support, invitational. Opener knows their own five-point range exactly, so accepting or declining is arithmetic rather than a guess.
4♥ / 4♠13 or more with four-card support. Opener has at most 15, so the partnership holds 24-28: game, and nothing above it worth investigating. Bid it and stop talking.
Game on three13 or more with only three-card support still bids game opposite a five-card major. Eight trumps and 24 points at worst is a game contract, and opener cannot hold more than 15.
A new suit11 or more with a five-card suit, forcing. Below 11, prefer 1NT: a limited opening opposite a limited response rarely wants to be at the two level.
1NT6-10 with nothing better to say. Opposite a limited opening this is a real contract rather than a waiting bid: opener is not about to jump to game with a hand you know nothing about.
2♣ / 2♦ by a passed hand (Two-Way Drury)After a third- or fourth-seat 1♥/1♠, the passed hand's 2♣ shows 10-12 with exactly three trumps and 2♦ the same with four or more - artificial, the same convention as Standard American. Opener's cheap return is the minimum; over 2♣, 2♦ confirms a sound 13-15.
2NT11-12 balanced with no fit. Opposite 11-15 that is 22 to 27: game if partner is near maximum, too high if not, which is precisely the question 2NT puts to them.
3NT13 or more balanced, no fit and no suit of your own worth naming. Opener is capped at 15, so there is a game here and almost never more.

Notice how much of this table ends the auction. Opposite an opening that could hold 21, none of these bids would be safe; opposite one capped at 15, almost all of them are simply the answer.

WHEN THEY INTERFERE

Your system under fire

When a Precision pair opens and the opponents interfere, the conventions that protect the auction are part of this system, written out here in full so Precision reads and changes independently. One carve-out: over the strong 1♣, the values scheme above replaces all of this - the tools below apply to the limited openings (1♦, 1♥, 1♠, 1NT, 2♣, 2♦) whose auctions work like natural ones.

THE CORE TOOL

Negative doubles

When partner opens and RHO overcalls, a double by you is negative: it shows the unbid suit(s) rather than penalty. It's the single most important competitive convention over the limited openings: it lets you compete for a fit without jumping the auction past a comfortable level.

1♦–(1♥)–1♠A real spade suit of four or more, forcing for one round - every four-card-spade hand comes through here, however strong. Opener raises with four, bids 1NT with their hearts held, shows a second suit, or rebids the diamonds as the conventional nothing. (Over the strong 1♣ the values scheme applies instead - this is for the natural 1♦ only.)
1♦–(1♥)–DblDENIES four spades - with four or more you bid 1♠ yourself. The double shows values (6+) with four cards in clubs: a hand that wants to compete but has no spade suit to name.
1♦–(1♠)–DblPromises four or more hearts - the one unbid major - so opener can count the heart fit exactly and answer in it with four.
Through a low-level overcall (e.g. 1♦–(2♣)–Dbl)Shows the unbid suit(s) instead of penalty, typically both majors 4-4, or a single 4+ card major, roughly 6+ HCP.
Through higher-level overcallsMost partnerships play negative doubles through 3♠ (or “as high as it's practical to define”), with the promised strength scaling up as the overcall gets higher, there's less room to show a suit and compete again later.
What it does not promiseExtra length beyond 4 cards, or extra values beyond a minimum at the higher levels. Read a low-level negative double as “I can compete,” not as a guaranteed big fit, unless the rest of the auction confirms it.
Converting to penaltyEven at the two level, a double stays takeout by default - it's not an exception. Your partner does have the option to pass and convert it to penalty, but that's realistic only when the opponents' point count is unusually well-defined, such as after an opposing 1NT opening: a known, narrow range makes it possible to judge you're sitting over real tricks rather than guessing.

BIDDING INSTEAD OF DOUBLING

Responder's other options over an overcall

New suit at the cheapest level (a “free bid”)Non-forcing in modern style, a decent suit, not enough to insist on game opposite a minimum opener. Bidding at all already shows something in a competitive auction, so this doesn't need to promise as much as it would uncontested.
Jump in a new suitForcing, real extra values, since nothing required competing at all.
Cuebid of the overcaller's suitTwo meanings, by what partner opened. Over a major opening: the classic limit raise or better in partner's suit. Over a minor opening and their major overcall: game-forcing with four cards in the OTHER major - the minor may be three cards, so the cue hunts the major fit first, and the same four cards with less than game-forcing values go through the negative double instead.
1NTA stopper in the overcaller's suit plus roughly the uncontested 1NT range, shaded down slightly since bidding at all already promises something here.
PassDenies enough to act. With a genuinely weak hand, passing and trusting opener to reopen (often with a double) is completely normal: see Reopening below.

THEY DOUBLED PARTNER'S OPENING

Responder after a takeout double

When partner opens one of a major and RHO doubles, the ordinary raise structure stops working: a simple raise now covers everything from a hand competing on air to a hand worth an invitation, and opener cannot tell them apart. Their double solves the problem it created: a hand that wanted to bid notrump naturally can redouble instead, which frees both notrump calls to describe raises.

New suit at the one levelA five-card suit that can still be shown at the one level goes in before any raise: their double makes the raise tempting, but a suit passed over now is buried for good, and the raise is still there next round.
RedoubleTen or more points and no fit worth showing. It says the hand belongs to us, and it is the one call in this structure that is about the point count rather than the fit: with support, every rung below describes the raise better.
1NT, constructive raiseThree or four trumps with about 6-8. The notrump range is freed up entirely by their double, because a hand that wanted to bid notrump naturally can redouble instead. Says “I have a fit and a little something” without using up the two level.
2NT, limit raiseAn invitation to three of the major, and nothing above it. Not “limit raise or better”: a hand worth more bids the game directly rather than inviting one and hoping partner reads it. This is the Jordan / Truscott convention.
Jump raise (2, 3 or 4 of the major)Preemptive, not invitational. Raise to the level of the total trumps: nine trumps to three, ten to four. It takes room away and says nothing about values, which is exactly what makes 1NT and 2NT readable.
Game raise on shapeFour-plus trumps with a six-card side suit headed by the ace or king, or five trumps with a void. Bid the game. The point count badly understates these: a control in a suit long enough to establish is a source of tricks once trumps are drawn.
New suitNatural and non-forcing. With the raise ladder carrying every hand that has support, a new suit here is a suit, not a stopgap.

This applies over a major, not a minor. A minor opening does not promise five cards, so raising it is not the known eight-card fit the structure is built on.

ANSWERING THE RAISE

Opener, once responder has raised

Both notrump raises are limited at the top as well as the bottom, which makes opener's next call close to arithmetic: partner has promised a range, and opener knows whether the sum of the two hands reaches game at the bottom of it, only at the top, or not at all.

Two of the trump suitThe sign-off. Even the top of partner's range leaves the partnership short of game, and repeating the agreed suit at the cheapest level says exactly that.
Three of the trump suitThe general invitation, and not forcing, partner may pass it. Right when no single side suit is where the contract will be decided.
A new suit (2♠, 3♣, 3♦ over hearts)The trial bid: an invitation that is also forcing for one round. It names the suit where partner's help would do the most good: three or more cards with neither top honour, where a king opposite turns two losers into one. Better than the general invitation whenever such a suit exists, because it asks a question partner can actually answer.
Four of the trump suitEven the bottom of partner's range is enough for game. Nothing to ask about, so name the contract.
Control bids past gameOnly when a slam can actually be there. A limited raise puts a ceiling on the partnership, and a control bid over a game already agreed does not merely ask a question: it removes the contract that was already right, pushing a sound four-level game to the five level.

Responder then answers the trial bid:

Bid the gameEither because this is the top of the range already shown, or because of help in the suit partner named, a top honour there, or a shortage to ruff with once trumps are drawn. The question was about that suit, not about the point count.
Return to the trump suitNo help and no extra values. Partner may pass. An invitation everybody accepts is not an invitation, so declining has to be a real option.

WHAT A RAISE IS WORTH

The values move with the shape

The thresholds above are not one number. What a raise is worth depends on the shape far more than on the point count, and the bigger the fit the less the count tells you.

Four trumps, no shape9-10 high card points to invite. A flat hand has to have the values, because it has nothing else to offer.
Five trumps and a shortageTwo points lighter. The shortage takes a trick the count never sees, and the fifth trump is what lets you use it.
Four or five trumps and a six-card side suitLighter again, and with a top honour in the long suit, bid the game rather than inviting. Partner opens 1♠, you hold ♠Kxxx and ♥Axxxxx with seven points: that is 4♠, doubled or not.
Which points, not how manyWhere the honours sit decides whether a marginal hand is worth the invitation. ♠KJ875 ♥842 ♦63 ♣A63 is eight points, and every one of them works: king-jack in the trump suit and an outside ace. That is a sounder raise than nine points spread across queens in the suits the opponents have bid, and it is worth 2NT rather than a preemptive jump.
Why not support pointsSupport points price a singleton the same whether you hold four trumps or five, which is precisely where the equivalence breaks down. For super fits the high card count is a weak guide: singletons and voids decide it.

THEY DOUBLED THE RAISE

Opener, when partner's raise is doubled

2NTExtra values, roughly 15+, with a long minor and their suit stopped, the suit they have actually named, not just any major. Where the call was a takeout double and they named none, the majors are what the double promised, so those are what need stopping. Better than jumping in the minor: it shows the strength, keeps 3NT in reach when nine tricks are the right target, and leaves room to return to the minor if the opponents name a suit you cannot stop. Not with a four-card unbid major: that is the more useful thing to say, because it can find an eight-card fit and notrump cannot.
A jump in the minorAnswers the strength question with the strain question still open. It takes the room the partnership needs and contracts for eleven tricks when nine may be all that is there.
3NT over a takeout doubleNeeds the majors stopped, not merely the suits they have bid. A takeout double promises the unbid suits and names none of them, so the stopper test has to include them: otherwise the doubler is sitting with a running major on lead.

PARTNER CUEBID

Answering the cuebid of their suit

What the cuebid askedAdvancer's cuebid of the opponents' suit shows a limit raise or better in the overcalled suit. It is an invitation, so it is answered by how much this hand has beyond the minimum an overcall already promised: not by repeating the suit as cheaply as possible whatever it holds.
Sign offCheapest level in the overcalled suit. A minimum: the hand is what it already claimed to be, no more.
JumpRoughly 12+. More than the minimum an overcall guarantees, without committing to a game partner may not have the values for.
Bid the gameRoughly 14+. An overcall promises little, so the bands sit below where they would opposite an opening: two hands that good belong in the game rather than signing off and hoping partner bids again.

A BETTER FIT, LATER

Opener's second suit

Opener bids a second suitAfter responder has raised, naming a new suit (usually an unbid major) looks for a better fit rather than settling for the first one. A major that goes unmentioned at the two level is rarely findable later.
Responder supports itFour cards in that suit is an eight-card fit nobody had found yet, and it outranks the fit already agreed when it is a major. Raise to the cheapest level with a normal hand: partner bid at the two level, so the cheapest raise is already the invitation, and jump to game only on a genuine game count.
Counting the raiseHigh cards against partner's promised minimum for the game decision, because the two sides of that sum have to be in the same unit, adding your support points to partner's high-card minimum counts a shortage in your hand as though it were honours in theirs. Shape is allowed for separately, at a higher bar: a level bought by a shortage needs more of it.

EXACTLY THREE, NOT FOUR

Support doubles and redoubles

After opener rebids and responder shows a suit, if RHO now doubles or overcalls, opener's double (or redouble, if RHO doubled) is a support double: it shows exactly 3-card support for responder's suit, as opposed to bidding it directly, which would show 4. That precision matters when responder is deciding whether to compete further.

Support double (after RHO overcalls)Exactly 3-card support for responder's suit and real extra values (about 15+). Bidding the suit directly instead would show 4: the double preserves that distinction, and a minimum opener simply passes.
Support redouble (after RHO doubles)Same idea one notch up: shows 3-card support after the opponents have doubled responder's suit.
Cuebid of their suit (opener's strong raise)Four-card support for responder's major and about 17 or more: too much for the direct jump to game, which would end the story. The cheapest bid of their suit promises nothing in it and everything in partner's - game values at least, with slam still in the picture if partner has extras.
Responder rebids the majorWith five cards opposite the three the double promised, name the major again rather than raising opener's minor, an eight-card major fit beats a longer minor one, because ten tricks are cheaper than eleven. Constructive and not forcing: the first response promised nothing in high cards, so bidding again over their competition is what shows the values.

FAST DENIES, SLOW SHOWS

Lebensohl

Lebensohl is the standard tool for a natural two-level overcall (2♦, 2♥ or 2♠) of partner's 1NT opening. One distinction runs through the whole convention: a direct three-level call denies a stopper in their suit, and the slow route through the artificial 2NT relay shows one. The game-forcing threshold is about 12 opposite Precision's 13-15 notrump. The same framework covers their conventional gadgets (DONT, Cappelletti): every such 2♦/2♥/2♠ that promises the suit it names is treated as a natural overcall of that anchor suit, and Lebensohl applies unchanged.

Their double of our 1NTSystems ON, whatever the double means (DONT's one-suiter included): Stayman, the transfers, the Stayman-then-2NT invitation and the direct games all keep their normal meanings, and a strong balanced hand simply bids 2NT or 3NT as it would have anyway.
Redouble over their doubleThe run to a minor, not a values card: weak (0-7) with five or more clubs or diamonds. Opener must bid 2♣, a puppet that says nothing about clubs; responder passes with clubs or corrects to 2♦, to play. If they bid over the redouble the puppet is off, opener passes, and responder names the minor only if it is still cheap.
Their 2♣ over our 1NTSystems stay on: DOUBLE is Stayman (same 8+ and a four-card major), and the 2♦/2♥ transfers are untouched since both bids are still available. Opener answers the Stayman double one step up, passes to convert with four good clubs, or bids 2♦ to deny; after the answer, responder invites or bids the game on ordinary arithmetic. A redouble is not a legal call over a bid, so the minor runout exists only over their double.
Their two-suited 2♦/2♥/2♠ (DONT, Cappelletti)Treated as a natural overcall of the ANCHOR suit - each of those bids promises the suit it names - so Lebensohl applies exactly as against a natural overcall, and doubles of the known second suit stay penalty-oriented.
2 of a suitNatural sign-off with a weak hand (0-7), available only when the suit outranks theirs. To play; partner passes.
DoublePenalty: four or more of their suit sitting over the overcaller, with the values (9+) to defend. Partner's narrow notrump range is what makes this a judged double rather than a guess.
Direct suit bid at the 3 levelNatural and game-forcing, and it denies a stopper in their suit. Fast denies: a real suit and the values, but nothing to hold up notrump.
Direct cue-bid of their suitStayman: game values with a four-card major, and no stopper. Opener names a major or falls back on notrump.
Direct 3NTTo play, and it denies a stopper. The values are there and nothing else describes the hand.
2NT, the relayArtificial puppet: opener must bid 3♣. Two kinds of hand travel this road, the weak one about to sign off and the game-going one with their suit stopped - slow shows.

After the relay: 1NT – (2x) – 2NT – pass – 3♣

Opener's 3♣ is compulsory, and responder's next call places the hand.

PassSign-off in 3♣: the relay was heading here all along with long clubs and a weak hand.
A lower suit than theirsSign-off. The relay let a weak hand compete at the three level without ever sounding strong; opener passes.
3NTTo play, and - because it took the slow road - it guarantees a stopper in their suit.
Cue-bid of their suitStayman with the stopper shown: game forced, four-card major sought, and notrump safe if no fit comes to light.

THE LAST WORD

Reopening and balancing your own auction

When your own opening gets overcalled and the auction comes back around to you (partner passed, RHO passed) you're in the reopening seat, a close cousin of balancing seat. With extra shape or strength, especially shortness in the opponents' suit, reopen with a double (showing support for the other suits, exactly like a normal takeout double) rather than let a partscore go by uncontested. Reserve an outright pass for hands with no realistic play for anything else.

UNDER PRESSURE

Interference over an ace ask

Slam auctions are the most attractive time for the opponents to interfere, because your responses are step-based and steps are exactly what a bid takes away. The counters are simple, and completely useless without a prior agreement.

Why they interfereBidding over an opposing 4NT is cheap and effective: it removes the responding steps the partnership was relying on. Expect it, and agree the counter before you need it.
DOPI (they bid over our 4NT)Double = 0 key cards, Pass = 1, then the cheapest bid = 2, next = 3. "Double 0, Pass 1": the name is the mnemonic.
ROPI (they double our 4NT)Redouble = 0 key cards, Pass = 1, then steps upward as usual. "Redouble 0, Pass 1."
DEPO (higher-level interference)Some partnerships prefer "Double = Even, Pass = Odd" when the interference is high enough that step responses would carry past the slam. Cruder, but it keeps you below six.
The real defenceNot asking in the first place. If the opponents are bidding actively, a control-showing auction leaks less and survives interference better than a convention whose steps they can take away.

Bridge Sense does not yet grade auctions where the opponents interfere over 4NT — the engine handles ace asks in uncontested auctions only. The conventions are here because you will meet them at the table long before the coach can mark them.

RANGES

1NT and its answers

1NT is 13-15So the invitational threshold moves. Opposite 15-17 you invite on about 8; opposite 13-15 that hand is a pass, and the invitation starts around 11.
Stayman and transfersWork exactly as they do elsewhere, 2♣ asks for a four-card major, 2♦ and 2♥ transfer to hearts and spades. Only the point requirements shift.
2♣ is a real suitBecause the strong artificial bid is 1♣, the two level is free to mean what it says. Raise it with support; bid a five-card major with 11+ before settling for clubs.

The full structure

Stayman and transfers are the ones everyone knows. What moves is the arithmetic: every threshold sits about two points higher than it would opposite a 15-17 notrump, because opener has two fewer points to bring.

2♣, Stayman10 or more with a four-card major, the bottom of the invitational band. The threshold is two higher than opposite a 15-17 notrump: opener has at most 15, so an eight-count has no game to look for.
2♦ / 2♥, transferA five-card major. Bidding the suit below yours makes opener declare it, which keeps their 13-15 hidden from the defence. The 1NT opening itself may hide a five-card major (5-3-3-2) or a good six-card minor (6-3-2-2, two of the top three).
After 2♣ - 2♦ (no major)2♥ / 2♠ invitational (10-11) with five of the suit bid and four of the other major: opener passes or raises to game with three-card support by range, 2NT or 3NT without it. 2NT invitational. 3♣ / 3♦ natural with five-plus, game forcing (12+): opener bids 3NT, or raises with four-card support and a maximum. 3♥ / 3♠ Smolen.
After 2♣ - 2♥ / 2♠Over 2♥: 2♠ invitational with four spades and not four hearts; 2NT invitational denying four spades; 3♥ invitational raise; 3♠ / 4♣ / 4♦ splinters with four-plus hearts and slam interest (15+). Over 2♠: 2NT invitational; 3♥ artificial slam try with four-plus spades, usually balanced (opener 4NT with a maximum, 4♠ otherwise); 3♠ invitational raise; 4♣ / 4♦ / 4♥ splinters. In both, 3♣ / 3♦ are five-plus and game forcing. Opener answers a splinter by asking keycards with nothing wasted facing the shortness and more than a minimum, otherwise the game.
After the transfer is completed2♠ after 2♦ - 2♥ is five-five in the majors, invitational: opener bids the better major game with a maximum and a fit, and with a minimum passes holding spades, bids 3♥ holding hearts, or 2NT. 3♣ / 3♦ show four-plus of the minor with the five-card major, game forcing: opener bids four of the major with three, raises the minor with four and a maximum, else 3NT. 3♠ / 4♣ / 4♦ (hearts) or 4♣ / 4♦ / 4♥ (spades) are splinters with six-plus trumps and slam interest. Super-accept: opener jumps to three of the major with a maximum and four trumps; responder passes a bust, bids the game with anything more, and asks keycards in the slam zone.
2NT opening (22-24)3♣ Stayman. Over 3♦: 3♥ / 3♠ Smolen, 4♣ / 4♦ five-plus with slam interest. Over 3♥: 3♠ is the artificial slam try with four-plus hearts, 3NT offers the choice of games promising four spades (opener with four corrects), 4♣ / 4♦ slam interest. Over 3♠: 3NT to play with four hearts, 4♥ the artificial slam try with four-plus spades. 3♦ / 3♥ transfer; after the completion 3NT is exactly five (choice of games), four of the major six-plus to play, 4♣ / 4♦ four-plus of the minor with slam interest, 3♠ (hearts route) five-five with slam interest, 4♥ (spade route) five-five choice of games.
2♠ / 2NT, minor transfersSix-plus cards in the minor, weak or game-going: 2♠ to clubs, 2NT to diamonds. Opener's step below the completion is the super-accept with honour-led support, inviting 3NT on a running minor. Responder passes or corrects when weak; a three-level new suit is game-forcing with at most a singleton there, and opener places 3NT or five of the minor by whether the short suit is covered from the strong side; 3NT signs off; four of the minor tries for slam. Invitational balanced hands still go through Stayman and then 2NT.
3♣ / 3♦, game-forcing shapes3♣ shows five-five in the minors, 3♦ six diamonds and four clubs, both forcing to game. Opener picks 3NT or a fitting minor with a maximum.
3♥ / 3♠, shortnessGame-forcing 5-4-3-1 with a void or singleton in the major bid and three cards in the other; opener reads where the honours work.
Smolen and the 5-5 majors routeAfter 2♣ - 2♦, a jump in the four-card major shows five of the other, game forced. With 5-5 in the majors and game values, transfer to spades and then bid hearts.
4♣ / 4♦, slam askSix or more hearts (4♣) or spades (4♦) with strong slam interest - seventeen or more opposite 13-15, or thirteen with a strong seven-card suit, or even ten when the seven-carder comes with a side singleton or void - the 33-point rule is a notrump rule, and a hand with a long strong suit counts its slams in winners, not points. (Not classic Texas, which maps 4♦ to hearts and 4♥ to spades: here both game bids stay natural.) Opener's cheapest step shows a maximum - and three aces count as a maximum whatever the point count, because a long-suit slam ask is asking about controls; the trump game denies. 4NT then asks keycards in the major the ask set.
4♥ / 4♠, to playA six-card suit with game values and no slam interest (12-13), or a hand whose game is written in shape - a seventh trump, or a sixth with a side singleton or void. Opener passes.
Transfer, then 4♥/4♠The mild slam try: 14-16 with six trumps. The direct raise to four was available as a signoff, so taking the transfer route first and jumping says game values with a little more. Opener passes with a minimum or a doubleton, and asks keycards with a maximum, three-card support, and every side suit controlled.
They double the transferThe lead-directing double changes nothing about the obligation: opener completes. And it can upgrade responder's hand - their double marks the missing honours in the suit it names, so a responder with no king, queen or jack there has nothing wasted, every point working, and a mild try becomes a keycard ask.
…then 2NT or three of the majorThe same structure every system uses: 2NT invites with exactly five and leaves the strain open, three of the major invites with a good six. 3NT and four of the major are the game-going versions. Only the count shifts: opposite a 13-15 notrump responder needs about two more than they would opposite 15-17.
The invitation, via Stayman10-11 opposite 13-15. With 2NT now a transfer to diamonds, the balanced invite travels through 2♣ and then 2NT - opener reads the sequence exactly as the old natural raise.
3NT12 or more. 12 opposite 13-15 is 25 at worst, with no major fit to look for.
PassUnder 10. That is 24 at the very most: opposite a 15-17 notrump the same hand would be worth a move, and here it is not.
Opener answers StaymanName a four-card major, or bid 2♦ to deny one. Hearts first when holding both, so a spade fit can still be found below game.
Opener accepts3NT with 15, maximum for 13-15 opposite an 11-12 invitation is 26. At 13 or 14, pass.

THE NARROW OPENINGS

Answering 2♣ and 2♦

These two openings describe a hand more precisely than anything in a natural system, 2♣ is a real club suit with 11-15, and 2♦ is both majors with a diamond shortage. The responses are correspondingly concrete: with a weak hand you are usually choosing where to play rather than asking anything.

2♣, passUnder 11 opposite a long club suit and at most 15. Two clubs is a perfectly good place to stop.
2♣, 3♣Club support (6-12) without a clear game to name. Raising takes room from the opponents; opener moves over it with a maximum and a suit to show.
2♣, a majorA five-card major with 11 or more, forcing. A major-suit game is far likelier than eleven tricks in clubs.
2♣, a new suit11 or more with a five-card suit of your own. Forcing, and it lets a limited opener choose between the two fits knowing exactly what you hold.
2♣, 2NT11-12 balanced. Game is on if opener is near the top of 11-15 and off if they are near the bottom, which is the question being asked.
2♣, 3NT13 or more with the stoppers. Partner's clubs provide the tricks, and with opener capped at 15 there is no slam to hunt for.
2♦, pick a majorPartner holds four of each major and at most one diamond, so with a weak hand simply choose the one you hold more of. This is not an invitation (it is selecting the trump suit and stopping.
2♦) game11 or more. Partner promised four, so there are eight trumps at least, and their diamond shortage opposite your length is exactly the ruffing value that makes the game play.
2♦, passNo major worth choosing and not enough to look for game. Their diamonds are short so this will not play well, but neither will anything else available.

OBSTRUCTION

Weak twos and preempts

Precision alters the strong and limited openings, not the preemptive ones: a weak two is 5-10 with a good six-card major here as anywhere, and a three-level opening is a standard preempt on a seven- or eight-card suit below opening strength. The one specialty at the top end is Namyats, where 4♣ and 4♦ carry the strong four-level majors.

Raise the weak twoNine trumps between you and not enough for game. This is not an invitation: it is obstruction taken while it is still cheap, and partner is expected to pass.
2NT, feature askGame is possible but the fit is not there. With a maximum and an outside ace or king partner names that suit; with a minimum they sign off in their own.
Game over a weak twoA fit and 15 or more. Partner has six of them and 5-10: that is enough, and a limited opening has already told you everything it is going to.
Game over a three-bidA seven-card suit opposite 15 or more with a fit is a game contract. Partner has described tricks and few defensive values; add and place it.
3NT over a minor preemptPartner's long minor will run once set up and you hold the other suits. Nine tricks in notrump beats eleven in the minor.
PassThe preempt was aimed at them, not at you. Without the values for game, raising the level only turns their problem into yours.
Opener bids againAlmost never. You preempted, which bid the hand to the level it was worth: partner knows the range and the length, and bidding on unprompted is how a preempt stops being one.

ROUND TWO

The second call

After a limited opening, the second round of bidding is unusually quiet, and that is the point rather than a gap in the method. Both hands were described within a few points on the first call, so the arithmetic that decides the contract has already been done.

Accepting an invitation14-15 accepts, 11-13 declines. The range is narrow enough that this is arithmetic rather than judgement, which is the whole dividend of a limited opening.
Raising partner's majorFour-card support: to the two level on a minimum, the three level on a maximum. Keeping the raise proportional is what keeps the 11-15 promise intact.
Rebidding your suitSix cards in the suit already shown. Repeating it adds length without adding strength, which is exactly what a limited hand should be saying.
1NTBalanced, minimum, nothing new to say. It keeps the auction low, which is where a limited hand with no fit belongs.
Pass, but never over a forcing bidThe commonest second call in the system, and a feature rather than a shortage of ideas: opener's range was known within five points before responder spoke, so if the arithmetic did not reach game the first time, another round will not change it. The exception is absolute: a new suit from responder is forcing, and being limited is no exemption from answering it. A limited hand that passes a force is not being disciplined, it is leaving partner's question unanswered.
Raising a major on three cardsEnough here, where it would not be in a system with more room. A limited opening gets no second chance to find the fit, and the alternatives on that shape are a notrump rebid that buries it or a pass that ends the auction.
A second suitFour cards in a suit nobody has bid, through the three level. Partner has to hear about it now or not at all.
Finding the levelEach of these is bid at whatever level is still available rather than at a fixed one, a response at the two level does not leave opener with nothing to say, it just means the same message costs one more step.
Responder passes a gameOpener bid game and their range was already known. There is nothing left to describe and nothing to gain by moving.

HONESTLY

What it costs

What you gainOpener's strength is known within about five points immediately, so responder can judge the level on the first call. Strong hands are never passed out. Constructive auctions are shorter and more accurate.
What you give up1♣ conveys no shape, so a strong hand describes itself a round later than in a natural system. Two natural bids (1♣ and 2♣) are spent on other duties.
The real costThe opponents know 1♣ is strong and artificial, and it is the most-defended bid in bridge. Expect interference, and have an agreement for it before you meet one.
Who it suitsPartnerships willing to learn a structure rather than bid naturally. The gains are real but they are gains in accuracy, not in simplicity.

UNCHANGED

What doesn't change

Entering THEIR auction is identical in every system: overcalls, takeout doubles, Michaels, the Unusual Notrump and balancing all apply exactly as written on the Competitive bidding page. Defending your own auction - Lebensohl, the doubles, the forcing pass - is part of this system and covered above.

So is slam bidding: Precision pairs play Roman Key Card 1430, the same as most 2/1 partnerships. One Precision extra: over a notrump REBID, 4♣ is Gerber, asking for aces up the steps (4♦ none or four, 4♥ one, 4♠ two, 4NT three). Never over the 1NT opening itself - there 4♣ and 4♦ are the slam asks in the majors, in every system. And everything on the Concepts page (hand evaluation, the Law of Total Tricks, what game actually requires) is system-independent by definition.

Try it

Switch the system to Precision on the practice page and bid some hands. The difference shows up fastest on a limited opening, where responder can place the contract in one call.

Practice a hand