Stagnation was originally interpreted as a shelter woven with bamboo, wood or other things, and later extended to crisscross, such as Cen Can's famous poem "The sand sea deepens with unfathomable ice, the clouds are bleak, and Wan Li condenses". In other words, dry ice is used to describe the interlacing of solid ice.
At first, it was vertical and horizontal. The beads of Selected Works of Zuo Si _ withered. Liu Yuanlin's notes are dry, but they are still vertical and horizontal. Later, it can also refer to railings. For example, Li Bai's "Qingpingdiao" in Tang Dynasty, the agarwood pavilion is north.