What is the shelf of calligraphy?

Shelf, also called shelf structure, refers to the structure of a word itself.

Calligraphy practice has three stages: stippling, framing (structure) and composition (layout). Dot is a combination of words, strokes and parts; Rack is the structure of single words, especially the structural arrangement or art of combined words; Composition is the overall layout design when combining words into chapters and articles. Different stages, different emphases.