1. A kind of bounding paper used for writing inscriptions on stele. Draw a "well" shape in the square grid to form nine equally divided grids. Because the shape and position of the nine grids are similar to the nine palaces in the ancient Mingtang, hence the name. It is said that this method was created by Ouyang Xun, a famous calligrapher in the Tang Dynasty. Jiang Ji of the Qing Dynasty continued to create a new style of nine palaces, with thirty-six squares divided equally into one square. See Chen Yizeng's "Essentials of Hanlin" in the Yuan Dynasty and Jiang Ji's "Continued Calligraphy Theory" in the Qing Dynasty.
2. Refers to the divided chant pattern of the poem. The poetic meanings of the upper and lower lines are completely different, and the words are closely matched. The content and form interact in a complex manner, just like the nine palaces in the ancient Mingtang, hence the name.