Several useful but mostly nameless conventions and treatments.
Want to investigate slam after finding a fit with Stayman, but don’t have the right hand to ask for keycards? Bid the other major at the three level, e.g.
1NT - 2C
2H - 3S ... or
1NT - 2C
2S - 3H
Opener can now cue bid, life is good.
Inverted raises try to cover a broad spectrum of supporting hands with just two bids, not ideal. Because we don’t need 1D - 3C to show an invitational club hand we can use it in a way that discribes four raise ranges…
1D - 2D 6-10
1D - 3D 11-12
1D - 3C relay to 3D
The latter auction is used on preemptive hands with less than six points or game going hands, indicated when responder makes another bid after opener’s 3D rebid. (Note that showing diamond support after 1D - 2C is strong and forcing.)
To avoid possibly wrong-siding 3NT after a minor suit 2/1 we respond 2NT with an appropriate 13-15. Supporting hands are not precluded. The rest of the raise schedule looks like …
1M - 3M weak
1M - 3C limit raise with 4 or 3 and a short suit
1M - 3D 16+ points
Because of our unusual 1C opening, 1D -1S, 2H is the only natural reverse we have to deal with. The 2H reverse is forcing, but not to game, and promises a rebid. Responder’s rebids at the three level promise 10+ points and are forcing to game. Responder’s 2S rebid (showing 5+ cards) and 2NT are also forcing but the auction may be passed out if opener rebids 2NT, 3D or 3S. Other rebids by opener are forcing to game.
Opener’s rebid of 2D after 1C - 1D shows some undefined game going hand (that standard bidders would have opened 2C.) Opener’s 2D rebid after 1C - 1H or 1C - 1S similarly shows a game going hand but can be somewhat weaker as responder is showing 6+ points. In both of these auctions responder’s rebids are natural with one exception …
When responder is unable to make an economical constructive rebid (given the limits that the 1D bid imposes) he rebids 2H, waiting, or possibly showing hearts. (Note that, because there wasn’t a 1NT response (showing 9-12), a 2NT rebid after 2D must show 6-8 points.)
Responder rebids two of the unbid major to show any 10+ point hand and strongly suggest slam prospects. Other rebids are natural and limited to 6-9 points.