These numbers are always written as two digits, with a leading zero if necessary, and the easting is always followed by the northing. Thus, 4 letters and 4 digits give the position of any 1-minute quadrangle. Each of the 1-minute quadrangles may be further divided into 10 or 100 smaller divisions both north–south and east–west, permitting the identification of 0.1-minute or 0.01-minute quadrangles. The GEOREF coordinate for any 0.1-minute quadrangle consists of four letters and six numbers; the GEOREF coordinate for any 0.01-minute quadrangle consists of four letters and eight numbers. The initial two letters of a GEOREF reference, designating the 15 degree quadrangle, can be omitted, if it is clear which 15 degree quadrangle the reference applies to (e.g., when working within a restricted geographical area). Example For example, on a GEOREF chart, Naval Air Station Patuxent River (38°17′10″N 76°24′42″W) / (38.286108, -76.4291704) is located (to the nearest minute) at position GJPJ3417. To locate the position from the coordinates, proceed as follows: Right from 180° longitude to longitude zone G Up from the South Pole to latitude zone J Right in zone GJ to the lettered 1° column P Up in zone GJ to the lettered 1° row J Right in the 1° horizontal zone to 34 minutes Up in the 1° vertical zone to 17 minutes The same co-ordinate shown in 6-digit (1/10 minute) format is GJPJ342171 and in 8-digit (1/100 minute) format is GJPJ34241716. Designation of area Extensions to the above notation allow the GEOREF system to be used to designate an area around a reference point. This is achieved by adding an area designation to a base GEOREF co-ordinate. The area designation can be the letter S, to specify the sides of a rectangle (separated by the letter X); or the letter R, to specify the radius of a circle. In both cases the units are nautical miles. In addition, the letter H can be added, followed by an altitude in thousands of feet. For example, the reference GJQJ0207S6X8 designates a rectangle centered on Deal Island (GJQJ0207), running east–west and north–south. Designation GJPJ4103R5 means a circle around Point Lookout (GJPJ4103) with a radius of . Designation GJPJ3716H17 means a height of 17,000 feet over GJPJ3716. See also List of geodesic-geocoding systems Global Area Reference System (GARS) Maximum elevation figure correlated to each GEOREF quadrangle on VFR aviation maps Military Grid Reference System (MGRS) Area minimum altitudes