Object

In TAD, every element that occupies space is represented as an object. Hence, an enclosed space is an object.

In TAD, all objects are well-formed objects.

Shape

By definition, a shape can be an open shape or closed shape. Open shapes include lines and angles. Closed shapes include triangles, squares, rectangles, and other polygons. If any closed shape is made up of open shapes, the closed shape is an ill-formed shape. If the closed shape is holistic and complete in nature, it is a well-formed shape.

In TAD, all the shapes are well-formed.

Volume

Traditionally, a volume is associated with a solid object that has mass. In TAD, even voids are objects. Hence, the space within a room is also a volume.