《晋书·志·第六章》
三分所生之律长，增加一分，产生上生的律；减少一分，产生下生的律。
三分所生，益其一分以上生；三分所生，去其一分以下生。
The length of the scale produced by dividing by three increases by one part, producing the upper scale; decreases by one part, producing the lower scale.