A linear form is based on a linear element, is a 3D object with six sides, and is derived from a base line. The base line is determined by the placement of at least two data points which set the orientation (or direction) of the form. A linear form can be straight, curved, or segmented. The existing linear form's base line element can be a line, line string, arc, circle, block, shape, or polygon. The linear form can be modified in length, height and width, and the top face can be realigned to almost any angle or profile.

Since a linear form is generic in nature, it can represent many element types across many disciplines including architecture, civil, mechanical, and the plant and process industry. Linear forms can more explicitly represent walls, concrete slabs, steel tanks, roof profiles, and structural beams when part definitions are assigned to them.