Literature Reference: The Chanyu accompanies the military tent, and the Rizhu guards the ceremonial barrier. Source from 'Xing Wugong Qingshan Palace'.
单: Delicate, pure, and unadorned. Here it refers to the virtuous character or graceful appearance of a person.
于: Thus, it is.
Meaning: Chanyu refers to the supreme leader of the ancient Xiongnu, symbolizing authority and leadership.