Jacoby 2 NT
Developed by Oswald Jacoby. 2 NT response to Major opennings means 13+ points and 4 cards support, and asks to opener if he has any void or singleton. Opener bids his void or singleton in 3rd level. If he does not have any void or singleton then he bids game with minimum openning value, bids 3 NT with 15-17 points, or invite to slam by bidding 3 Majors with 18+ points.