《宋书·志·卷十一》
漠灵帝熹平六年，宫中的束观召见典律者太子舍人张光等人询问有关准的情况，张光等人不知道。
灵帝熹平六年，东观召典律者太子舍人张光等问准意，光等不知。
In 177, during the reign of the last emperor of the Han, an official named Zhang Guang was summoned to court to discuss the zhun, but he was unable to explain it. 