Eight characters: it is the year, month, day and hour measured by stem and branch.
Stem and branch are primitive counting tools in ancient China, which have a wide range of uses. It is composed of ten stems and twelve branches, (the least common multiple is 10, and the least common multiple with 12 is 60), and it has 60 cycles, so it is called sixty flowers.
Ten days of work: A, B, C, D, E, Ji, G, Xin, people, ghosts.
Twelve earthly branches: Zi, Ugly, Yin, Mao, Chen, Si, Wu, Wei, Shen, You, Xu and Hai.
For example: 20 16- 12-24-09: 00.
Timing: Bingshen Gengzi Chen Geng Xinsi
In this way, eight words make up 20 16 19: 00 on February 24th. It's called horoscope.