Like SAYC, BBO basic depends upon hand evaluation using the high card point method. Hand shape adjustments are made for long suits when bidding a new suit, and for short suits when showing support for partners bid. Other similarities to SAYC include:
Five-card majors: opening a major suit promises at least five cards in that suit.
Weak two bids: two-diamond, -heart, or -spade opening bids are made with a six-card suit and 6 to 10 high-card points. The bid promises two of the top three honors in the suit.
Strong two clubs: a 2 opening bid is artificial and promises 22 points or more.
Pre-emptive openers: including weak-three bids and weak-four bids similar to the weak two-bids but showing additional length.
Notrump openers show a balanced hand with the following point ranges:
0 to 12 HCP: pass, unless the hand is suitable for a preemptive opening bid.
13 to 21 HCP: hands of 13 HCP or more are strong enough to open with natural bidding, including:
* minimum opening hands with 13 to 15 HCP
* medium opening hands with 16 to 18 HCP
* maximum opening hands with 19 to 21 HCP
For unbalanced hands with 22+ points: show a very strong opening hand by using the strong 2 convention.
For balanced hands, open with a no-trump bid when you can limit your hand to the following point ranges:
15 to 17 HCP: 1NT
20 to 21 HCP: 2NT
25 to 27 HCP: 3NT
For other balanced hands, opener can indicate points by opening in the longest suit and then bidding no-trump for the second bid:
13 to 14 HCP: bid 1 of a suit and then make a no-jump rebid in no trump
18 to 19 HCP: bid 1 of a suit and then make a jump rebid in no trump
22 to 24 HCP: bid 2 and then make a no-jump rebid in no trump
28 to 30 HCP: bid 2 and then make a jump rebid in no trump
31 to 32 HCP: bid 2 and then make a double-jump rebid in no trump
Responder approximate hand strengths
The responder also communicates hand strength through bidding by responding to partner's opening bid uniquely according to their high card points.
0 to 5 HCP: a hand in this range normally should not be bid unless partner opens with the strong 2 convention.
6 to 9 HCP: this is a minimum response hand. Responder can show support for partner's bid with a simple raise to the 2-level, bid a new suit but only at the one-level, or respond 1NT.
10 to 11 HCP: any new suit bid at the 2-level promises opening partner at least 10 points. With 10 or 11 points, responder has a medium-strength hand, and can bid another 4-card suit but at the two-level, now in hopes of discovering the 8-card fit, planning eventually to "invite" partner to a game contract.
12 or more HCP: you have a maximum hand and desire a game contract. Responder has the bidding space available to search for a fit and share additional information that may lead to a slam contract.
Responding with a minimum hand
First priority is to show 3-card support for partner's 5-card major; respond 2 of the major with 6-9 points. Bidding 4 of the major immediately is preemptive and shows 6-9 points with 5-card support and at least 1 singleton or void in a side suit.
Next priority is to bid the longest suit at the 1-level, promising 6-9 points and at least 4 cards in that suit. Do not go to the 2-level with less than 10 points.
Show support for partner's minor suit opening if you have 5-card support by responding with 2 of the minor. Bidding 4 or 5 of the minor is preemptive and shows 6-9 points with 6-card support and at least 1 singleton or void in a side suit.
When responder cannot support partner's bid, the response is 1 NT, to show a bad fit and no more than 9 points. This gives partner the choice of passing and playing in 1 NT or changing to a partial game in another trump suit.
Responding with a medium hand
First priority is to show 3-card support for partner's 5-card major; so, rebid partners suit at the 3 level. This "limit raise" skips the 2-level, specifically to indicate 10 or 11 points; shows an 8-card fit in partner's major trump suit; and invites partner to make a game bid with more than minimum opening strength.
Next priority is to bid the longest suit.
Show 5-card support for partner's minor suit opening by responding 3 of the minor.
Responding with a maximum hand
Your partnership should be in a game-level contract when responder adds a minimum of 12 points to partner's promise of at least 13. Unlike Standard American Yellow Card, where a strong jump shift is recommended, responder shows a very strong hand in BBO Basic by using the "principle of slow arrival". This means keeping the bidding low and showing support for partners suit with two sequential bids:
Bid another suit first at the lowest level, show a long or a strong suit.
With the second bid, show support for partner's suit. Even if partner supports responder's first bid, responder should bid partner's suit to indicate the 8-card fit and game-level points.
Responding with balanced hands
A no-trump response to partner's opening bid indicates point information and lack of suit length:
response of 1NT shows 6 to 9 HCP, no support for partner's suit, and no 4-card bid;
response of 2NT shows 13 to 15 HCP, no support for partner's suit, and no 4-card bid;
response of 3NT shows 16 to 18 HCP, no support for partner's suit, and no 4-card bid.
Opener's response to partner's search for a fit
Often, in response to a natural opening bid in the 13-21 point range, the responder will suggest a new suit at the one level. While this promises 6 points or more, information is needed to make the optimum contract. If opener has 4-card support for responder's new suit, then opener should show support but also has the burden of showing his hand strength so that responder can choose the best contract:
minimum opener : bid at the 2 level.
medium opener : bid at the 3 level, inviting game.
maximum opener : bid at the 4 level.
Examples :
1 – 1 – ; 2 – Pass – : both partners have minimum hands but find a major fit.
1 – 1 – ; 3 – Pass – : opener has hearts and extra points, and invites game; but responder has only a minimum hand.
1 – 1 – ; 4 – Pass – : opener has game values.
1 – 1 – ; 2 – 4 – : opener has minimum hand, but responder has game-going points.
1 – 1 – ; 3 – 4 – : opener has extra points and invites game, and responder has extra points and accepts.
