What do you mean, guarding the grave is better than opening a cow?

Open day: the open day of twelve satellites.

Twelve satellites: construction, separation, full, leveling, determination, holding, destruction, danger, success, combination, opening and combination.

Twelve satellites can be found in the yellow calendar.

Cattle don't guard the tomb: it means that the god beast doesn't guard the tomb.

Days when Anoplophora longicorn was not buried: Gengzi, Xinwei, Renshen, Gui You, Wuyin, Jimao, Renwu, Guifei, Shen Jia, Yiyou, Wu Jia, Yi Bei, Shen Bing, Ding You, Renyin, Guimao, Bingwu, Ding Wei, Wushen, Ji You, Gengshen and Xinyou.

This sentence probably refers to the choice of the "open" day in the twelve satellites and the day when the longicorn does not keep the tomb.