What does the meridian of ancestral graves represent?

Meridional direction of ancestral graves: The ancestral graves face south or face south.

Meridian: refers to the north and south. The ancients regarded Zi as due north and Wu as due south.

Don? Su Shi? "Tang Chang 'an Ximing Temple Tower Monument": "In the middle of Yin and Yang, the meridian is straight, surrounded by temples. "