Very strong and artificial openings. Opener bids
2C = shows either (a) 26-29 HCP and balanced hand, and opener will bid notrump to show this at next rebid, OR
(b) 25+ HCP and an unbalanced hand, and opener will bid a suit to show this at next rebid
Responder bids
2NT = not even 1 quick trick
A suit = at least 1 quick trick and length in the suit bid.
Opener bids
2D = shows 22-25 HCP balanced.
Responder bids
2H = asking bid whether opener has maximum or minimum (2NT shows minimum, 3TN shows maximum).