A ray is occasionally referred to as a half line. Rays begin at one point and continue indefinitely in a single direction after passing through another point. Similar to the methodology described above, a single arrowhead overbar is used to denote a ray. Accordingly, the ray above may be denoted as DE or DF The notations above are read as "Ray DE" and "Ray DF" respectively. The first letter represents the endpoint while the second letter represents another point on the ray.