"Tang Yun" uses Yu and Zhun to rhyme, "Ji Yun" uses Yu and Zhun to rhyme, pronounced the same as Yin. "Shuowen Jiezi" explains it as: the appearance of a distorted face. Also, "Ji Yun" uses Yu and Min to rhyme, pronounced the same as Yun. 䪳頵 refers to an uneven and unstraightened face. Also uses Yu and Yi to rhyme, pronounced the same as Yi. The meaning is the same.