《宋书·志·卷三十》
左五年间，屐齿突然间都不贯通屐底，这称之为 阴卯 。
太元中，忽不彻，名曰： 阴卯 。
During the five years of the Zuo era, the teeth of clogs suddenly no longer extended all the way to the clogs' base, and this was known as "hidden base".