A convention for replying to partner’s 1♥ or 1♠ opening that has fallen into disuse. It uses both 4♣ and 4♦ as conventional raises of opener’s major, both with four trumps, game values and two aces. The 4♣ bid shows an extra feature: a third ace, a singleton or the king of trumps. The 4♦ bid denies those extra features.
