Symbolically, the minor and major arcs are denoted by the following:

• Minor arcs, which measure less than a semicircle, are represented by its two endpoints
• Major arcs, which meaure more than a semicirlce, are represented by three points. The first and third points represent the endpoints while the middle point is any point on the arc located between the endpoints.

The semicircle represents an arc whose endpoints coincide with endpoints of the diameter.  The semicircle is represented by three points using the same methodology to represent a major arc.