In Song poetry: within fifty-eight characters are Xiaoling, from fifty-nine to ninety-nine characters are middle tune, and beyond ninety-one characters are long tune.
The words are long and short sentences, but the number of words in the whole article is certain. The tone of each sentence is also certain. Ci can be roughly divided into three categories: (1) Xiaoling; (2) Middle tone; (3) Long tone. Within fifty-eight characters are Xiaoling, from fifty-nine to ninety-nine characters are Zhongtone, and beyond ninety-one characters are Long-tone. The difference is in the number of words, but there is no difference in the rhyming techniques. There are already some middle tones and long tones in the Dunhuang tune lyrics. Liu Yong wrote some long tunes in the early Song Dynasty. Su Shi, Qin Guan, Huang Tingjian and others followed, and long tune became popular. The characteristics of long tunes, except that the words were originally called "quci" or "quci", are set to music. From the perspective of accompanying music, it is the same literary genre as Yuefu poetry and also comes from folk literature. Later, like Yuefu, Ci gradually separated from music and became a different style of poetry, so some people called Ci "Shiyu".