First make certain that NO other BETA opening bid other than 1♣ or 1N is appropriate - if there is then one must prefer it.
Now a decision between 1♣ and 1N must be made. If 1N satisfies all rules then it must always be preferred to a 1♣ opening.
In the case of 1N after making all necessary HCP adjustments. BETA uses only a 12-14 1NT opening.  In beta good 3rd hand 12-14 1N openings are encouraged BUT we will not shade to 11 HCP.
BETA's 1♣ opening is usually 12-18 but maybe shaded to a good 11 in third or fourth opening positions. With 18+ prefer a 2♦ opening]

The distribution restrictions on our 1N openings must be adhered to in all positions these are:: No 5 card Major or Diamonds, No void or singleton, at least 4-3 in the minors, a 3 card minor and should ideally be headed by one of A¦K¦Q and allowed distributions are 2245, 2236, 33{43}, {24}{43},  {23}44,  {23}35.
So we prefer 1N whenever we can instead of 1♣ with its mild pre-emption it offers. The theoretical reason for this preference is that the IN opening may contain a single 4 card Major about 20% of the time with a distribution of {24}{34} - an ideal 1N distribution. So are {23}44 & {23}35.
Now {34}{33} hands are normaly opened 1♣ and not 1N unless majority honour strength is held in the minors.

The limitations Beta places on a 1N opening are aimed at practically preparing for a safe minor suit exit from 1NT * as partner can bank on finding at least 3 card minor suit support with transfers of PASS for 2♣ & ** for 2♦
A 2♣ staymanic inquiry can be made to get further high precision of the shape of the 1N opening with replies: 2Ma: 4 cards; 2♦: 4 cards; 2N: 4-5 Clubs and 3♣ rare with 6 Clubs
These restrictions  have reduced the % occurrence of a 1NT opening in BETA to be significantly lower: c7%  than its occurence in ACOL. On the plus side a significant increase in the frequency of a 1♣ opening - this fits very well with the mathematical  'theory of information' - and Beta makes use of this advantage to its limit. See our 1♣ opening for full details.

An importance aspect of our 1NT opening lies in taking off a significant load from 1♣ openings. It also allows the bidding continuations for 1♣ and 1NT to be tailored to the nature of these openings - leading in practice to totally different sequences.