Genealogy.
The genealogy is what is usually called the Sheng Geng Book.
For Sheng Geng, see "Sheng Geng Bazi". Sheng Geng Bazi, an idiom, refers to the birth date. To explain the words separately, Sheng Geng can be seen in the "Bazi Sheng Geng". BaZi is a Chinese fortune-telling method. Superstitious people believe that the year, month, day, and time of a person's birth are all matched by the heavenly stems and earthly branches. Each item is replaced by two characters, and four items have eight characters. Based on these eight characters, a person's fate can be calculated. In the old custom, men and women must first exchange eight-character posts, also known as "geng posts", or simply "eight-character posts" when they get engaged.