Five-card majors for offensive purposes. However, if the trump cards break 4-1 or 1-4, then drawing trump will result in no trumps left for offensive purposes. The value of five-card majors can be understood then on two levels: But five-card majors have several drawbacks: Both partners must agree to follow the five-card major bidding treatment on their opening bid. Opener must have at least five cards in hearts or spades to start the bidding with that suit. Responder is expected to show support with three-card support, indicating an eight-card fit. With only four cards in a major suit, the opening bidder is
Singaporean bridge and this is not a universal rule - is in no-trump games, the winner of the bid will begin the game. The other less-agreed-upon rule is the drawing of trumps. Some people play by the rule that the drawing of trumps can only begin when the player drawing trumps already has a void suit or when trump has been broken (i.e. a trump card has already been played), some play by the rule that drawing can be done at any point in the game, while most play by the rule that trumps can only be drawn when the trump suit