RESPONDER'S REBID AFTER A VERY STRONG GAME-FORCING 2NT REBID FROM OPENER (STARTED WITH MAJOR)
The general principle is that the big unknown hand, opener, is in control. The exact nature of their game-forcing hand isn't yet known and will be revealed later in the auction, be it a huge single-suited hand with opener, a fit with responder or whatever. Responder should try to describe their hand and answer opener's questions.
|3 of partner's major||Natural, 3-card support, less than intermediate strength.|
|Rebid||Natural, 5-card suit.|
|New suit||Natural, shows second suit.|
|3NT||Denies having any other shape-showing bid available. Doubleton at most in partner's major, can't rebid own suit (ergo four-card suit only) and has no second suit that they regard as biddable (presumably suppressing a worthless four-card suit).|
|4 of partner's major||Natural, 3-card support, intermediate strength or greater.|
|Other bid||Normal meaning, e.g. Splinter, Exclusion Blackwood, RKC Blackwood in opener's suit.|