XY Notrump/Two Way New Minor Forcing
After opener bids a suit, responder bids a second suit, and opener rebids notrump, responder bids
-2C: Art. with game invitational hand. Says nothing about clubs. Demands 2D. (To play 2 diamond / limit). Opener must bid diamonds
-2D. Responder then bids
-2H : four card hearts plus limit raise values
-2S : four spades plus limit raise.
-2NT : limit raise that denies a four card major
-3C : Limit raise showing 5+ clubs
-2D : Art. game forcing. Says nothing about diamonds.
-2H : To play if partner had opened hearts. Otherwise it asks for support in one of the other two suits.
-2S : To play if partner had opened spades. Otherwise it asks for support in one of the other two suits.
-2NT : Limit raise of notrump.
-3C : To play. Shows 6 card club suit & unspecified four card major if one has not been bid yet (if it has, then you know which four card major it is; if only one major hasn't been bid, you can probably guess which one it is).
-3D : Weak limit. Shows 6 card diamond suit & unspecified four card major if one has not been bid yet