Lines that extend to infinity in one or both directions, known as rays and construction lines, respectively, can be used as references for creating other objects.
- A construction line (also known as an xline) is a linear object that passes through two points and extends to infinity in both directions.
- A ray is a linear object starts at a point, passes through a second point, and extends to infinity.
Both construction lines and rays are ignored by commands that display the drawing extents.