Analysis of Beta 1-level Openings

1st & 2nd position opening  requirements are in order of preference:

1S:         10+ HCP   Requires 5+ card suit upper limit is either our 2S opening: a strict 4-5LTC count and some shape requirements OR our 2D multi opening balanced with 19-20 HCP or 2N balanced 21-22HCP or 2C unbalanced <4LTC
1Sbis:    4-7LTC     Requires 5+ Spades & 5+ Clubs: Requires mandatory rebid of 3C.
1H:        10+ HCP   as for 1S above
1Hbis:   10+ HCP  Requires precisely 4-4 in Majors. Upper limit is 18HCP. our 2D  multi covers 19-20 & 2N 21-22 or 2C: 23+Note: This includes 44{41} hands too
1D:        11+ HCP   Requires 5+ card suit. Balanced hands limited by 2D multi with 2N rebid & 2N opening. Unbalanced hands <4LTC limited by a 2C opening
1Dbis:    4-7LTC    Requires 5+ Diamonds & 5+ Clubs: Requires a mandatory rebid of 3C.
1N:        12-14 HCP Balanced. Further shape constraints: 7-9minor cards, 3card minimum in each miner with a top honour. Also Not suitable for any of the above openings 
1C:        12+ HCP   Strictly nsuitable for a 1N opening or any of the above.
PASS:    0-11 Be prepared to PASS unless suitable for any of our weak openings: 
With a 6 card Major open 2D;
With a 7 card Major consider a 3Ma pre-empt;
With a (7)8+ card minor suit consider a 4mi pre-emptive opening. Note Beta does NOT have 3mi pre-emptive openings
This is the most frequent of all opening bid so it deserves some mention! It describes a hand unsuitable for any other system opening bid and partner must bear this in mind in subsequent bidding.

Other general considerations:
1NT opening is an adjusted 12-14. Lower for flat 4333 or being Aceless or for 3+ Jacks. Augment with 2+ Aces or a good 2+ significantly supporting 9's and 10's
Minimum 1C|D openings that lack either a 4 card Major or are Aceless unless containing a 6+ card minor which allowing a rebid of 2mi.
1suit openings should be adjusted -1 HCP when Aceless.

Aproximate Frequency of the 1-level Beta opening bids are as follows:

1C:    15.5%
1D:    8%
1H:    7.5%
1S:     7%
1N:    5%

Total for 1-level openings is: 43%

Average frequencies for Beta 2-level openings are (wider variations occur):

2C:    2.25%
2D:    4.5%                includes weak Major 2's
2Ma:  3.25% each
2N:    1.75%

Total for 2-level openings is: 15%

Other openings: (considerable larger variations can occur)

PASS:        36%
3mi:            0.75%   each
Pre-empts:  3%        includes 3Ma, 3N, 4mi
4Ma:           0.75%  each

Toatal Others: 42%

Actually as Beta has evolved the % of an opening PASS bid  has dropped considerably and a 1C opening has dramatically more frequent.

Alertable Openings
1C     alertable as it can be just 2 cards. In principal is forcing but Majorless near Yarboroughs can be passed
2C     alertable as a near game bid. Also strictly forcing
2D     multi is alertable 3-way
2Ma   alertable 4-5 LTC
3mi     are alertable as 5-5 or better in RED or MAJOR suits 4-7LTC

Principals behind responder's continuations to opening bids:

Direct 4 card support to Major openings must be shown immediately
Over 1C, 1D and 1Heart openings showing a major of 4+ cards  is a priority -  with both show the Hearts first regardless of length!
1C is forcing if any major showing response is available. 1N is a negative response denying any Major (PASS if RHO bids usually denies Majors) and * would show the presence of an unbid Major
If 1N is doubled, 2mi by responder are escape bids and redouble asks opener to choose the better minor.

Beta handles interference bids by opponents in the following ways:
With support for partner - competitive raises,
Trustcott: 2N showing support and values to compete soundly at least at the 3-level.

Negative Doubles: deny a fit in partner's suit & suggests interest in unbid suits. Opener is free to choose:  rebid (6 cards), bid a second suit, make a limit bid in NT's. This is typical of our usage of  'Negative Doubles'. Which also operate over higher level interventions too but are not usually suggestive of penalties unless following a weak jump o'call. However negative doubles will always promise minimum values as follows: At 1-level 8+, 2-level 10+, 3-level 12+ HCP.
Also PASS may be the only bid available in Beta with substancial values|length in the opponents suit - relying on partner to re-open with a double!
Please note that doubles in 1C sequences are not Negative! - but usually signalling a specific Major holding.

If opponents open the bidding. Its a different scene altogether in Beta!
Holding 2 5 card suits see our comprehensive means to show both suits in one bid, A T-O * is another weapon of importance, our multi 1NT overcall handles other possibilities, and simple o'calls are natural.usually 5 card, however may also be a 4 card Major....

In the cases of 1mi openings the basic sequences are all about locating Major fits:  4-4 5-3 or 6-2! A major piece of the armoury is a wide ranging NT rebid (12-16) by the opener if a 4-4 fit has not been discovered in order to test a 5-3 fit through a 2C inquiry requiring a 9+HCP count or direct rebis with 6 cards. See 1C & 1D details.
In the case of a 1H opening a direct fit in hearts must be shown when holding 4+ cards, otherwise 1S must be bid if 4+ cards are held. See details in 1H opening.

A weak partner with a 6+ card minor suit and NO Major suit can bid a minor break-out by jumping to the 3-level! Beta does not make jumps in new suits as responder to show force!  A 2-level bid is considered forcing.

For full details with all other possible responses see these openings.