The plane coordinates of a point on the earth’s surface, used in expressing the position or location of that point in the appropriate zone of this system, consists of 2 distances, expressed in units of U.S. survey feet and decimals of a foot. One of these distances, known as the “x-coordinate”, gives the position in an east-and-west direction; the other, known as the “y-coordinate”, gives the position in a north-and-south direction. These coordinates depend upon and conform to the coordinates, on the Illinois Coordinate System, of the monumented survey stations of the United States National Geodetic Survey within the State of Illinois, as those coordinates have been determined by that survey.