"Tang Yun" uses the characters "e" and "wai" for fanqie pronunciation, and "Ji Yun" uses "wu" and "wai" for fanqie pronunciation, with the same pronunciation as the character "hui". "Shuowen Jiezi" explains it as: blackness formed by irrigation. Also, "Guang Yun" and "Ji Yun" use the characters "wu" and "kuai" for fanqie pronunciation, with the same pronunciation as the character "kuan". "Yupian" explains it as: shallow black. "Guang Ya" explains it as: blackness. Also, "Ji Yun" uses the characters "huo" and "guai" for fanqie pronunciation, with the same pronunciation as the character "huo". The meaning of the character is the same.