The orthogonal projection of a line, on the ground, onto an east west axis of reference. The departure of a line is the difference of the meridional distances or longitudes of the ends of the line. It is east, or positive, and is sometimes called the easting, for a line whose azimuth or bearing is in the northeast or southeast quadrant. It is west, or negative, and is sometimes called the westing, for a line whose azimuth or bearing is in the southwest or northwest quadrant. It is abbreviated as dep. in notes.