Qian Tian is also called father, and Kun Earth is also called mother; one string is shaken to get a boy, so it is called the eldest boy; one string to Xun is to get a girl, so it is called the eldest daughter; another string to Kan is to get a boy, so it is called a middle man; another string to Li is a girl, so it is called a middle girl; three strings to Gen are to get a boy, so it is called a young boy; three strings to get a girl, so it is called a young girl.