A partnership may agree that this bid is "forcing" for one round; if the intervening opponent passes, opener must bid at least once more. This guarantees the responder at least one more opportunity to bid or pass. This mechanism allows the partnership to use the 1NT response for a greater variety of hands: in particular, "invitational" as well as "minimum" responder holdings. The forcing notrump is used over major suits only; 1NT is always standard and non-forcing over the minor suits.