One of a minor – 2NT should be a game force 13-15 HCP. This understanding keeps the bidding below 3NT for alternative game & slam exploration , which is the goal. This understanding allows contracts to be right sided for 3NT purposes.
A jump to 3NT which pre-empts partner should be a “picture” bid of a flat NT opener with soft values. We hate partner forcing the auction to the 4 level ( via a jump to 3NT ) just to force to game. Bidding 2NT to force to game is far more civilized and fits in with slow arrival showing strength.
What should we do with the balanced invitational hands in the 10-12 HCP range ? These are the hands that should be slotted into the inverted minor structure and identified via a relay. After partner takes the inverted minor relay , 2NT shows this hand type. Quite often with these kind of hands , you have a minor fitwith partner anyway.
Kx 
QJx 
1098x 
KQxx partner opens 1 so you bid 2 which partner must relay to 2. You follow up with 2NT and you have bid 1-P-2NT invitational but it just took longer. OK , lets review our inverted minor structure.
Inverted minors show all minor fits limit raise orbetter and include invitational NT hands in the 10-12 HCP range. Inverted minors with clubs , force a relay to 2and inverted minors in diamonds force a relay to 2.
The first job after the relay is to identify the invitational hands. 2NT after the relay , shows the 10-12 HCP range and a simple return to the minor suit should show the non forcing limit raise hands.
OK lets use artificial bids after the relay to show the strong minor hands. We will distinguish between game forcing hands with 5 card support or 4 card support. Lets use the spade suit to show the 5 card raises forcing to game…
| 1 |
P | 2 |
P | 1 |
p | 2 |
P | |
| 2 |
P | 2 |
P | 2 |
P | 2 |
P |
With clubs agreed we can use hearts to show the 4 card raise and the other minor ( clubs) after diamonds agreed to show the 4 card raise.
| 1 |
P | 2 |
1 |
p | 2 |
|
| 2 |
P | 2 |
2 |
P | 3 |
The only other thing on the menu is that we break the relay with the flat hands 18-19 and bid 2NT. This understanding “unclutters” the inverted minor structure. Inverted minors only deal with game forcing hands in partners minor or invitational hands in NT & partners minor.
Having 1NT-P-2NT as a game force , simplifies auctions as we know that all bids are forcing so they can be interpreted as showing distribution for alternative game contracts or as slam tries. You can find 4-4 major fits via this structure if you following the Kokish notion that only responder can try for the major fit. Bidding 2NT with soft values and a 4 card major should be allowed.