Okla. Stat. tit. 60, § 60-1002: Plane coordinate values

The plane coordinate values for a point on the earth's surface,

used to express the geographic position or location of such point in

the appropriate zone of this system, shall consist of two (2)

distances expressed in U.S. Survey Feet and decimals of a foot when

using the Oklahoma Coordinate System of 1927 and expressed in meters

or U.S. Survey feet and decimals of a meter or U.S. Survey foot when

using the Oklahoma Coordinate System of 1983 and expressed in

International feet or meters and decimals of an International foot

or meter when using the Oklahoma Plane Coordinate System (OKPCS).

One of these distances, to be known as the "x-coordinate" (also

known as "easting"), shall give the position in an east-and-west

direction; the other, to be known as the "y-coordinate" (also known

as "northing"), shall give the position in a north-and-south

direction. These coordinates shall be made to depend on and conform

to plane rectangular coordinate values derived from the National

Spatial Reference System (NSRS) as defined and promulgated by the

National Oceanic and Atmospheric Administration/National Geodetic

Survey, or its successors, and whose plane coordinates have been

computed on the systems defined in this act.