2NT shows trump support and 10+. An advantage with this is that 1maj-2maj shows 6-9 and an even hand , 1maj-3maj shows 6-9 and not balanced. If you play mini-splinter, 1maj-3maj would deny a single or void . This bid is very pre-emptive, specially after 1S - 3S.
After 1H / S - 2 NT:
- 3 K: Asking for points..
- 3 D: 10-12.
- 3 in the opening suit from the opener is to play.
- 3 in the other major asks for a singleton - and 3NT denies that.
- 4 in a new suit is cue-bid.
- 3 H: 13-15.
-Relay asking for singleton - and 3NT denies that. - 4 in a new suit is cue-bid.
- 3 S: 16-18.
-3 NT ask for a singleton .
4 in a new suit is cue-bid.
- 3 NT: 19+.
- 4 in a new suit asks for a cue-bid.
- 4 in a new suit: Void and 10-12.
- 3 in a new suit: Asking for controls. 3 in the opening suit is control asking in club.
If the opener has passes 3 in the opening suit is to play., 3C is control asking in club.
Further on 3 in a new suit:
1 step: no cotrol
2 steps: second, and so on.
- 4 in a new suit:: Void, minimum. New suit from the 2NT bidder is cue-bid.
More: 1 H - 2 NT - 4 H shows void in spade.