约定叫 meaning in Chinese

artificial call
convention

Artificial call ? is a bid , double , or redouble that conveys information ( not being information taken for granted by players generally ) other than willingness to play in the denomination named or last named ; or a pass which promises more than a specified amount of strength or if it promises or denies values other than in the last suit named
（人为）约定叫? ?一种定约、加倍或再加倍，传递信息（非牌手公认的信息），这种信息并不是指标示或最后表明要打的定约；或者是不叫表示特定牌力，或承诺或否认最终所叫花色以外（某种花色）的价值。