[nige1]

Charles Outred's modifiication of Mike Bell's opening structure:

• 1♦ = BAL 11-13 HCP or NAT 4+ ♦.
• 1N = BAL 14-16 HCP.
• 1♣ = BAL 17-19 HCP or NAT 4+ ♣.
• 2♣ - 2♦ - 2♥ - 2♠ - 2N = BAL 20-21 HCP (Kokish see below).
• 2N = BAL 22-23 HCP..
• 2♦ = BAL 24-25 HCP. or 5-9 HCP 6 M (Multi).
• 2♣ - 2♦ - 2N = BAL 26-27 HCP.

Kokish variant...
2♣ - 2♦ - 2♥ = BAL 20-21 HCP or NAT 5+ ♥ then responder rebids ...

• 2♠ = ART 4+ HCP or BAL 0-4 HCP,
• 2N = ART 0-4 HCP 5+ ♠.
• 3♣ = NAT 0-4 HCP 5+ ♣.
• 3♦ = NAT 0-4 HCP 5+ ♦.
• 3♥ = NAT 0-3 HCP 5+ ♥.

[raspeball]

fromageGB, on 2020-May-11, 14:26, said:

Yes, no invite, just 3NT or not. I use 2NT as compulsory transfer to ♣, and 2♠ asking for 4 card minor, 2NT denial. This is useful if you judge you need 4 card support for a minor slam, and aslo when you have a "weak both minors" takeout.

I do play 2NT after failed stayman to play. I think being able to find the major fit when a couple of points lighter than you otherwise would is significant, especially matchpoints against a weak NT field where everyone will be in the major partscore beating you in 1NT.

This simulation is interesting regarding the need for having a natural 2nt available for responder after bidding stayman.
link.

Your assumption that it is more important to be able to check for majors in matchpoint seems to be supported by this simulations.
But it does not seems it is as valuable in IMP. So I think in teams it makes sense to use 2nt for other purposes.

Say you have a hand like this:
♠Kxxx
♥xx
♦ x
♣Kxxxxx

If opener have fit to clubs this hand could be great, but with a non fitting hand not so good.

You bid:
1nt-2♣
2♦/2♥-2nt=4 spades, (5)6+ clubs. Could be mildly invitational to game(Opener bids past 3♣ with club fit), or gameforcing.

Advantages:
….Seems like this could reach a few good games based on fit that could be hard to reach otherwise. (Agree that this is a low frequency hand).
..More ways to describe the game going hands.



Other sequences:

1nt-2♣
2♦ ?

2nt=As described above.
3♣=4♠,(5)6+ diamonds.Mildly invitational to game, or gameforcing
3♥=4♥/5♠
3♦=5-5 in majors? (Or other bid that you are missing in your system)
3♠=4♠ and 5♥

You could also swap the meaning of 3♦ and 3♠ .The advantage is that this leaves responder more room with 5 ♥ if he is slaminterested:

1nt-2♣
2♦-3♦(5♥,4♠ forcing game)
3♥(heart fit)