Flint 3D, 3C, and 2D 

Flint 3D:
over a 2NT opening, a 3D response demands that opener bid 3H which responder may pass, bid 3S, 4C or 4D as signoffs. Other rebids (say 3NT or 4H) by responder are mild slam tries with a real diamond suit.

Flint 3C: 
This allows the partnership to play in 3D. A 3C response demands that opener bid 3D which responder may pass or bid a long suit as a signoff. A 3D response is then Stayman. This convention is similar to Gladiator (q.v.).

Flint 2D:
After a weak no trump opening, a response of 2D is used to invite game in NT or a minor suit. Responder has either: 
1) a long solid minor, or 
2) unbalanced hand with at least four cards in each minor

If responder has (1), responder rebids 3C with a solid club suit OR a solid diamond suit plus a club stopper, or responder rebids 3D with a solid diamond suit without a club stopper. If responder has (2), responder rebids his stronger major.

The 2D response is forcing to at least 3NT. Opener rebids:
* a four card major, or
* 2NT without one 
Over responder's rebid, opener may bid 3NT, show a stopper, signoff in four of a minor, or bid a minor suit game.