What is the thirty-six zenith?

Taoism claims that there are thirty-six highest sun stars in the Big Dipper.

The 36 highest solar stars are: Tiankui, Tiangang, Tianxian, Tian Yong, Xiongxing, Mengtian, Tianwei, Tianying, Tiangui, Tianfu, Tianman, Tianlong, Tianshang, Tianli, Tianjie, Tian Xiang and Tianyou.