Point responses. The 2D response shows 0-4 HCP. Rebid of the cheapest suit is a second negative, and no bids are forcing after that. Otherwise, we are forced to game. The 2H response shows 5-7 and is forcing to game. 2S is 8-10 and at least close to forcing to slam if a fit is revealed. 2NT is 11+ and forcing to slam.
Over the 2NT response by responder (11+), 3C is Stayman, and other suit bids are natural. Otherwise, opener either bids a five-card suit or no trump without a 5-card suit. (There is no provision for 4-4-4-1 distribution, so this should probably be the meaning of the jump-shift by opener, but we have never agreed to a meaning for the jump shift.) Over the 2D response, opener shows points by bidding 2NT with 22-23 or 3NT with 24+. Otherwise, the 2NT bid is neutral for points. Bidding is normal and unchanged (Stayman, Jacoby) over 2NT and 3NT bids by opener. (Except, we perhaps should play that the 3D response to 3C shows a 4-card diamond suit, but we have not agreed on this.)
First bid suit by either opener or responder shows at least five; second bid suit shows at least four.
After a 2D response, I think a simple raise should also be a second negative and unforcing, but we have not agreed on this.
Ideally, the weak hand will not bid 4NT. (However, systematically, if the opener bids 2NT he cannot ask for aces). When the responder initiates Blackwood, and the opener is still unlimited, 5NT tends to confirm all of the controls and allow the opener to bid the grand with extra. It is unlikely that responder actually wants to count kings, so the response to 5NT should not go beyond the slam suit (unless he is accepting the invitation to the grand).
2C-2S 3H-4D 4NT? 2C-2NT 3H-3NT 4D-4NT? I think there should be a preference to thinking of 4NT as Blackwood, and meaningless bids as a way to bid 4NT. Then, 4NT is natural when there are no meaningless bids left. I define a meaningless bid, roughly, as the second bid by responder when the opener has shown two suits, and any bid after everyone has shown two suits.
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