The date is subject to which of the twelve gods, the star god on duty and the twenty-eight stars.

These 28 stars are Hornwood Horn, Kang Jinlong, Nyctereute, Fangri Rabbit, Xinyue Fox, Tail Fire Tiger, Jishui Leopard, Muan Jing, Ghost Golden Sheep, Liutu Swertia, Xingri Horse, Zhangyue Deer, Winged Fire Snake, Lumbricus, Kuimu Wolf, Loujin Dog, Stomach Pheasant and so on.

Twenty-eight stars were originally used by the ancients to observe the movements of the sun, the moon and the five stars. They can be used as signs to explain the positions of the sun, the moon and the five stars, but now they are used in the yellow calendar to infer good or bad days.

Some stars have certain rules to follow. For example, the changes of some stars are closely related to the changes of seasons and meteorology, and the occurrence of floods and droughts and the abundance and sorrow of agriculture are also derived from this, which includes certain astronomical meteorology and agricultural science. This prediction can be further studied. Among them, the predictions related to political goodness are mostly assumptions. There seem to be some rules for astrologers to decide the good or bad luck of each imperial house. The rule is to name the stars according to their shape, size, brightness or color, and then make corresponding good or bad judgments according to these. For example, Petunia and Weaver Girl are all named after stars. From then on, their good or ill luck was mostly related to cattle, cloth and women. For example, "The Battle of the Yellow Emperor" said: Morning glory is dead, and Daniel is dead; The little star died, and the calf died of an epidemic. The Weaver Girl is the gorgeous residence of the main silk. If Samsung becomes bright, the world will be peaceful, and silk and silk will be cheap: if the stars are unknown, there will be worries behind the main silk, and silk and silk will be expensive. The shape of a star can be associated with different things, so the same star can have different views. Morning glory, for example, can also be imagined as a river drum (also called a heavenly drum). Since it is a river drum, it is related to the military. "The Battle of the Yellow Emperor" says that the star is the general and the left and right are the left and right generals. Therefore, he is considered to be related to the good or bad luck of the military and government.