Zelandakh, on 2012-March-06, 03:07, said:
2♠ - 2NT (feature)
========
3♣ = min with feature (then 3♦ asks with rebids 3♥=♥/3♠=♦/3NT=♣)
3♦ = no feature (then 3♥ asks, 3♠ min, 3NT max)
3♥ = max with heart feature
3♠ = max with diamond feature
3NT = max with club feature
In fact any response structure works that includes 3 hand types in 3♣ and 2 in 3♦ so long as you are careful with which hands have to be shown with 3NT. It is just a matter of deciding which hand types you might want to hide after a 3m response. For this purpose I think the negative responses (minimum or no feature) are best suited). Obviously you could substitute "shortage" for "feature" here if desired although in that case the immediate 3NT response really needs to be the "max without shortage" hand. Therefore
2♠ - 2NT (shortage)
========
3♣ = min without diamond shortage (then 3♦ asks with rebids 3♥=♥/3♠=♣/3NT=none)
3♦ = diamond shortage (then 3♥ asks, 3♠ min, 3NT max)
3♥ = max with heart shortage
3♠ = max with club shortage
3NT = max with no shortage
Obviously you could use this second structure for feature too by simply replacing the word shortage by the word feature throughout. In that case you show the diamond feature when sometimes you did not need to but in return are not committed to game opposite a club feature.
A problem with these schemes is that they commit you to game opposite some maxima. That's OK if you're trying to decide which gamer to play, but not if you're trying to decide whether to play game. My suggestion had that defect too, but only when it was a maximum without a feature, ie a solidish suit, where game is likely to be good anyway.