What does it mean to draw lots for signature in Huang San?

A name used for divination, usually indicating a sign.

The title of Huang San is just a legend. There are many kinds of historical materials and folklore (at least seven kinds), among which the most widely spread is the theory of Li Sizhi in Historical Records: Huang San is the emperor, Huangdi, Tai Huang and Fuxi, Shennong and Huangdi in Huang San recorded in Ancient Wei Shu.