2N  0-11 or 18+  兩低55+
    3m  to play(0-9)
    3H! 問牌型
        3S!     2S, 2155
        3N!     2H, 1255
        4m      6m
        4H      3H, 0355
        4S      3S, 3055
        4N!     minors 66+
    3S  問高低限, 通常已知那門為王牌
        3N      min
        4C      8-11
        4D      18+
    3N  S/O
    4m  PRE
    4M  S/O
    4N  6 key cards rkcb
    5m  S/O