Kokish

After 1-2 , 2NT asks partner what is the cheapest suit he would accept a game try in. If responder bids 3 Opener can still bid 3 or 3 to make a further game try in that suit.

If opener bids a suit instead of 2NT then it is a game try showing a singleton.

If the bidding goes 1-2 then 2 asks what is the cheapest suit he would accept a game try in and 2NT is a game try showing a stiff .

If opener has bid 2 over 2 as a game try then responder shows a stiff by bidding 2NT.