There are four line modes: Endpoints, Left Point, Midpoint, and Right Point. Depending on the mode you choose in either the Line tab (Item > Modify) or the Measurements palette (Classic or Space/Align tabs), line length and position will be described differently.

• Endpoints mode: The X1 field indicates the horizontal position of the first end-point; the Y1 field indicates the vertical position of the first end-point. The X2 field indicates the horizontal position of the last end-point; the Y2 field indicates the vertical position of the last end-point.
• Left Point mode: The X1 field indicates the horizontal position of the leftmost end-point; the Y1 field indicates the vertical position of the leftmost end-point.
• Midpoint mode: The XC field indicates the horizontal position of the midpoint of the line; the YC field indicates the vertical position of the midpoint of the line.
• Right Point mode: The X2 field indicates the horizontal position of the rightmost end-point; the Y2 field indicates the vertical position of the rightmost end-point.