What is the messenger in Su Wu's The Shepherd?

The shepherd in Su Wu holds a continuous knot in his hand.

Jingjie, an ancient festival held by messengers, is believed to be trustworthy. Later, it generally refers to symbols.

"The History of Emperor Guangwu of the Later Han Dynasty" Li: "Festival, so its letter is also. With bamboo as the handle, the handle is eight feet long, and the oxtail is a fork, which is triple.