The Design Elements hierarchy contains terms for conventionalized and recurring shapes and arrangements of forms used in the design of many types of object and their ornament, that may be expressed regardless of their materials (e.g., "rosettes," "Celtic crosses"). Relation to other hierarchies: Terms for certain attributes related to shape or position are in the Attributes and Properties hierarchy (e.g., "convex," "concentric"). Terms for three-dimensional ornamental components or elements that exist only in a given material are found in the Components hierarchy (e.g., "finials").