A 2C response to a third or fourth seat major suit opening...
...is Drury, artificial, showing a maximum pass and at least three-card support i.e., a limit raise.
If responder uses Drury, bidding 2C, what does a 2D rebid by opener show?
2D is artificial, confirming a sound opening bid.
If responder uses Drury, bidding 2C, what does a raise to 2 of the original suit show?
A sub-minimum opening; may only have 4 cards of the major suit.
Playing Drury, what do jumps to the three level in partner's major suit show?
Responder has 4 trumps and 5-8 hcp.