Elements of visual language

The authors propose a structural classification and vocabulary for visual languages. The visual grammar that comprises the elements of such a language is defined. The usual elements are composed of: (1) the visual alphabet, a set of visual primitives in a visual language; (2) the visual syntax, compositions of primitives to form visual statements; (3) interaction, user-to-system communications; and (4) structure, rules combining sublanguages into a language. The classification of the visual elements is viewed as a linguistic description of visual language.