The system we are playing is the Short Club (1♠, 1♥, 1♦ all promise a 5-card suit). I opened 1♠ and partner responded with 2NT. Now I know very well that she doesnt know the Jacoby 2NT convention. I also knew that she was showing real values. I bid out my shape, 3♦ was my second bid which partner lifted to 5♦. Dummy comes down and partner held 1444 (singleton ♠) and an opening hand as well. We were the only table that made the contract when everyone else was playing in 3NT which goes down 1. The ♠ suit was crummy; KQ and 3 babies. Partners singleton was also a baby. You get only 1 ♠ trick in 3NT.
See post 7 below.
In a Short Club system where 1♠, 1♥ and 1♦ all promise a 5-card suit, this bid actually fits in quite well. The 2NT bid over the suit opened promises a 4441 hand, a singleton in the suit opened and an opening hand as well. The probability of being dealt a 4441 hand and 12+ HCP is low at only 1.04%.
My question:
So what else could we use the 2NT bid for in a Short Club System?
1. Jacoby 2NT is the obvious one. But that can be accommodated in a different way as stated by aguahombre.
2. 11-12 HCP balanced and invitational.
3. 13-15 HCP natural and balanced, game forcing.
4. Mini-splinter or strong 16-19 splinter in any suit (as used by Zelandakh).
This post has been edited.