Kokish relay is the sequence 2♣-2♦-2♥-2♠. If this convention is on, a 2♥ rebid by opener after a strong 2♣ opening shows either ♥s or a big balanced hand (25+ HCPs). Responder must then relay to 2♠. If opener then bids 2NT, it shows a big balanced hand. Otherwise, it shows ♥s.