What is the mounting sequence of Chinese painting?

It specifically refers to the "hand scroll" mounting of China's paintings and calligraphy, which refers to the position of blank paper at the beginning of the picture scroll. It is the first painting and calligraphy by China. It acts like the second page in the cover of a book, and its length is about two-tenths of the frame. You can write on it. Because the first thing you see when you open a book is called "introduction".