1S Opening bid

♣ ♥ ♠ ♦

Requirements

Due to the critical need to enter the auction when holding a Major suit: the requirements are lower for the Majors by comparison to other suit openings: 1♦: 11+; 1♣: 12+;1N: 12-14.

1♠ is opened with 10 HCP with any 5+ card suit . 2♦ opening will cover 3-9HCP and a 6 card suit.
With 4-4 in Majors and 10+ HCP : Open 1♥ - See 1H opening bid. Partner is required to bid 1♠ even if a minor suit is longer. A direct Heart raise or minor suit bid or 1NT will deny holding 4+ spades!
Use judgement in deciding the choice of 1♠ or 1NT with these 4333 hands. Be prepared to PASS with 12 HCP with a weak spade suit and minors are not both headed by top honours. 1♠ is preferred wth some honour strength even with 4 cards while 1N is to be preferred if both minors are headed by a top honour.
5+-5+ in Spades-Hearts or Spades-Diamonds are opened 3♦ and 3♣ respectively.
5+-4+ in Spades-any other suit & a 4-5LTC are opened 2♠. This sets an upper limit on a 1♠ opening.

With balanced hands with 5 Spades we open: 2♣ with 23+; 2N with 21-22; & 2♦ with 19-20 & rebid 2N
Single suited hands with 5+ Spades and 3 1/2 LTC or less: Open 2♣ and rebid with a Spade Trump request
With 5+ Spades and 4 in any other suit with 4-5 LTC : open 2♠ and rebid +1 in the other suit if partner bids either 2N.
With 6+ Spades and 4-5 LTC: open 2♠ and rebid 3|4♠ with 5 or 4 LTC respectively, when partner inquires with 2N.
A 3rd hand opening of a weak 2♠ can be made on a 5 card suit.

Responses:
A direct Jump to 3 ♣|♦|♥: Shows a 7+ card suit weak 3-7 HCP - Break-out.
2NT: BARON (15)+ HCP response balanced hand (no 5 card suit) can be shaded to 15 ONLY with minimum support for Spades - Qx or better - 2nd step trump response. A Baron bid invites bidding up the line for both players up to 3NT. A rebidded suit shows 5+ cards any missed suit denies a 4 card holding.
Note: over any intervention 2NT becomes Trustcott showing 4+ card support and payable at least at the 3-level.
2♠: Needs minimum support: Hx or xxx & 4-8(9). This is can be somewhat pre-emptive or a sound raise. Opener can rebid in a new suit trial-bid. with 15+.
3♠: Limit BUT pre-emptive following intervention.
4♠: To play
4♣|♦: See SWISS bids. Shows 4-5 card spade support, a balanced hand & a solid raise to 4♠ - available even if opponents intervene! Note: In Beta direct splinter bids over opening bids are NOT used.
2♣|♦: Response shows a good 9+HCP. Minimum requirements are a 4+ card suit headed with Ace|King. This must be adhered to or partner may miss a game. This bid is Forcing. It may also be the debut of a DGR (delayed game raise) sequence shown by a rebiding 4♠ or by rebidding the 4th suit. Opener with additional values may investigate a slam. An alternative continuation arises when opener bids a 3rd suit - now 4th suit rebid by responder is a cue-bid also promising at least 3 card support for Spades with slam intent.
2♣|♦: Can also be a 6 card suit and 5-9 HCP. Subsequent Rebid of 3♣|♦ shows this and is a STOP bid (this is always true in Beta that when responder rebids his initial response!)
Cue-bid: When 1♠ was an overcall. This shows invitational values 13+ and <3 card spade support and no 5 card un-bid suit. Forcing for 1 round. Overcaller can rebid a 6 card Spade suit; show a second suit; else 2NT minimum.
2♥: Shows a 5 card suit & 10+ HCP
1NT: Ideally 5-7(8) HCP. No other bid available. If the 2♣ asking rebid is agreed, preferred with Beta, then the 1N range is extended to 10(11) HCP especially to cater for when holding a 5 card red suit. A 2♣! rebid (non-forcing) requests a 5 card red suit, or to choose between the black suits.
The logic behind the sequence 1♠-1N-2♣! Where 2♣ is artificial is given below,

Rebids by opener

There are 2 rebids in Clubs to take special note of:. The first handles 5-5 or better distributions in the Black suits:-

1♠-any-3♣ Shows 2-suiter 5+-5+ in ♠&♣ 4-7 LTC Responder may use 3NT to explore distribution or show preference. See theory

PASS Prefers Clubs
4♣ Invitational
3♠ or 4♠ To play
3N Distributional inquiry

The following gives a weak responder 5-9HCP a chance to declare a 5 card RED suit or to select preferred Black suit!1♠-1NT-2♣ Conventional bid. 1NT bidder to show a red suit if possessed - else to PASS(preferring Clubs) or bid 2♠ (preferring Spades)
[Important note: this conventional sequence is only available following a 1♠ opening]

2♦|♥ Usually a 5+ card suit, Natural (possibly a quality 4 card RED suit0 and unnattractive BLACK suit alternatives - opener may correct to 2♠ with 6 cards..
PASS Better Clubs 4+ & void, singleton or small doubleton in Spades - opener may correct to 2♠.
2♠ Flattish hand, weak - at least 2 card Spade support i.e. min: Hx or xxx

1♠-1NT-PASS Enough
1♠-1NT-2♠ To Play - probably 6 card Spades
1♠-1NT-3♣ Forcing, Natural 5-5 4-7LTC - 3N asks distribution can also be 6-5 or 6-6 Otherwise PASS or correct
1♠-2♣|♦|♥ -? Normally forcing responses 10+ HCP. UNLESS responder rebids his suit at his next bid.

PASS minimum. Usually only a poor fit & minimum 10 HCP or following a light 3rd suit opening bid
2NT 12-14(15) HCP Balanced. See detail conditions and alternatives in 2over1responses

3♣|3♦ |3♥ rebids are STOP bids & 6+ card suits WEAK.

UNBID minor: Conventional FORCING inquiry - confirms 1st response is positive 5+ card suit
3NT to play

3rd suit, 12+ 5-4 or better at 2 level. Responders options:

A rebid of 2NT denies fit in either of opener's suits. Attention: Promises 9+ only
Natural limit Raise of the 3rd suit.
3♠, Responder shows 3 card or Hx major support.
4th suit Forcing. a cue-bid & agrees Spades a powerful DGR sequence (unbalanced hand)
4♠ Promises 4 card support. A DGR sequence also implies an unbalanced hand and shortage in opener's rebid.

3rd 'suit' at 3-level without jump (over a 2/1 response) requires 15+ HCP. As this bid is "a new suit at 3-level" it is also GAME FORCING giving partner a free bid to further best describe his hand. See 2over1 discussion for further information. Responder may rebid to limit auction.
2♠ 10-11-12 HCP Minimal values, usually a 6 card suit
Jnew suit: (15)16+ HCP, short suit (2-3 cards) with top honour(s) - declares a single suited hand. This is NOT support showing
3♣|3♦|3♥ Show 4 card support. This is not Forcing but invitational (note partner has allowed for a 10HCP minimum opening - so with near opening values always consider game.
4♣|♦|♥ Invitational
1♠-3♠-?: 3♠ is not Forcing but invitational (note partner has allowed for a 10HCP minimum opening - so with good opening values always proceed to game. Similar situation:1 ♠-2X(opp)-2N-P-?: Same logic proceed to game with a good opening.