Chilli uses a restricted weak no-trump, showing a balanced hand with 12 to 14 points and no major suit. The rule of 20 is equally valid here: it makes sense to pass undistinguished 4333 12-counts.
There are several reasons for restricting 1NT to hands with no major:
- it allows a simple, systemic set of responses – no Stayman, no transfers etc
- it maintains the integrity of the system in that bidding past 1
and 1
denies the ability to bid either major - opening with the major suit (or opening an artificial one of a minor and following up with the major) allows more scope for using the technology provided for major suit fits such as splinters.
Responses to 1NT are entirely systemic. A 2NT response showing a minor two-suiter can be made with as little as four-four in the minors for the same Total Tricks reason discussed under the opening 1
.
NEXT: opening two of a minor