What is the meaning of "Xing" in Pipa Xing?

Line, a kind of classical poetry, is similar to Yuefu. Its syllable list is relatively free and the situation is full of changes. Wang Zhuo's Biji Manzhi in the Southern Song Dynasty explained: "Ancient poetry is called Yuefu, which means poetry can be sung, so there are songs, lines and songs in Yuefu."