Lebensohl Convention is a convention that can be used with good effect to combat
interference over an opening 1N bid. A similar system, based on Lebensohl, can
be used to respond to the take-out double of a weak two bid. You can also use it
after opponents has bid 1H-2H or 1S-2S.
2N response forces a 3C rebid which will be followed by a natural non-forcing
bid (or a pass when clubs is the suit) 0-8
while any bid made at the three level show invitational values (9-11
- 2N - (Pass) - 3C
(Pass) - 3D ; is now not forcing, natural with long diamonds.