Cappelletti is a method to describe various kinds of hands over a 1NT opener. Double is for penalties.
2C is a 1-suited hand. 2D = majors.
2H = hearts plus a minor.
2S= spades plus a minor.
2N = minors.

             S: AQxx
             H: x
             D: xxx
             C: AJ9xx
S: xx                  S: xxxx
H: AJTxx               H: Kxxx
D: KJxxx               D: x
C: x                   C: KQxx
             S: KJx
             H: Qxx
             D: AQxx
             C: xxx

W        N       E        S

2H       P       3H       P
4H       X       P/O