What is the sheep blade in the eight characters?

Sheep blade refers to: see Mao in A day, Chen in B day, noon in C day and E day, Wei in Ding day and E day, unitary in Geng day, Xu in Xin day, and ugly in Gui day.

There is a theory that the blade of the sheep in the second grade is Yin, the blade of the sheep in the fourth grade is Si, the blade of the sheep in the first grade is Shen, and the blade of the sheep in the fourth grade is Hai.