According to the AutoCAD for Design and Drafting documents1, the command that should be typed at the command line in order to start creating a line for drawing reference that starts at a defined point and extends to infinity in the designated direction is XLINE2. This command creates a construction line, which is a type of reference line that can help you manage accurate parameters of your drawing2. You can also use point objects as nodes or reference geometry for object snaps and relative offsets3.