Texas Natural Resources Code - NAT RES § 21.078. Terms “X Coordinate” and “Y Coordinate”

(a) The plane coordinate values for a point on the earth's surface, to be used in expressing the position or location of the point in the appropriate zone, of either system, shall consist of two distances, expressed in U.S. Survey Feet and decimals of a foot or varas or tenths of a vara when using the Texas Coordinate System of 1927 and expressed in meters and decimals of a meter, in U.S. Survey Feet or decimals of a foot, or in varas or tenths of a vara when using the Texas Coordinate System of 1983.

(b) One of these distances, to be known as the “x coordinate,” shall give the position in an east-and-west direction; the other, to be known as the “y coordinate,” shall give the position in a north-and-south direction.

(c) These coordinates shall be made to depend on and conform to the plane rectangular coordinate values for the monumented points of the North American Horizontal Geodetic Control Network as published by the National Oceanic Survey/National Geodetic Survey, or its successors, and whose plane coordinates have been computed on the systems defined in this subchapter.

(d) Any station described in this section may be used for establishing a survey connection to either the Texas Coordinate System of 1927 or the Texas Coordinate System of 1983.