What is your call with the South hand?

This is our very favorite convention. It is worth hundreds of matchpoints and hundreds of imps, but only a very few people play it. Basically, it goes like this:

If 2NT is not a raise of 1NT, treat it like a new suit, forcing one round.

Here are three examples:

(1)	1	1
	2	2NT
(2)	1	2
	2	2NT
(3)	1	1
	2	2NT

Notice that the original response doesn't have to be at the two level for this idea to apply. At one table, the bidding went:

West - pass pass	North 1 2 pass	East pass pass pass	South 1 3NT -
Opening lead: K. The opponents took the first five heart tricks, for down one

At the other table, the opponents bid these cards to five clubs and made six when the spade finessed worked. South bid a forcing 2NT over 2 and North bid 3, describing his hand. South probed with 3, showing strong spades and weak hearts. North retreated to 4 and South raised to game.