In the Jiyun (集韵), the characters "niú wěn" are used to represent the pronunciation of "yù" (rising tone). The Boya (博雅) explains that "wěn" means neat. Also, in the Jiyun (集韵), the characters "niú yǐn" are used to represent the pronunciation of "lú". Also, in the Guangyun (广韵), the characters "qú yǔn" are used to represent the pronunciation, and in the Jiyun (集韵), the characters "jù yǔn" are used, pronounced "jiǒng". The meaning is the same. Also, the Boya (博雅) states that "wěn" is the name of a type of jade. The Zhù (注) states that the pronunciation is "mǐn".