One No Trump (5)

Dealer South, EW Vulnerable

South	West	North	East
Bidding
1NT	No	2♣⁽¹⁾	No
2♦⁽²⁾	No	3♣⁽³⁾	No
3♥⁽⁴⁾	No	5♣⁽⁵⁾	No
No⁽⁶⁾	No

Explanations

⁽¹⁾ North has a game-going hand but a marked Diamond weakness, so proceeds via Stayman.

⁽²⁾ South denies a 4-card Major.

⁽³⁾ 3♣ now shows Clubs but expresses concern about one of the other 3 suits, asking South to bid stops upwards.

⁽⁴⁾ South shows his Heart stop, thereby denying a Diamond stop.

⁽⁵⁾ North now jumps to 5♣ knowing that 3NT is not going to make.

⁽⁶⁾ South knows this is a sign-off rather than an invitation to slam.