To Specify a Point Relative to a Series of Orthogonal Offsets
Start a command, such as the LINE command.
Hold down Shift and right-click in the drawing area, and choose Tracking.
Using an object snap, specify a temporary point.
Move the cursor up, down, left, or right until you see the rubber-band line.
The direction of movement affects the tracking direction. Notice that if you move the cursor from left to right, you must then move it directly over the last point specified in order to move it up or down.
Specify a second point or enter a distance. You can repeat these last two steps to specify a series of horizontal and vertical offsets.