The NRS is a system of waypoints developed for use within the United States for flight planning and navigation without reference to ground based navigational aids. The NRS waypoints are located in a grid pattern along defined latitude and longitude lines. NRS waypoint names are composed of two letters followed by two numbers, followed by a single letter. The first and second characters of NRS waypoints are the FIR identifier for the United States (“K”) and the FIR subdivision, or ARTCC center in which the waypoint is located (e.g. “D” for Denver ARTCC). The third and fourth characters are a number group representing the latitude of the waypoint. These numbers begin at the equator with 00 and advances north and south from 01 to 90 and correspond to every 10 minutes of latitude and repeating every 15°. The final character in the NRS waypoint is a letter representing the line of longitude for which the waypoint is located. This identifier starts at the prime meridian moving west to east and uses the letters A to Z while repeating every 26°. To date, the current density of the NRS grid is one waypoint spaced every 30 minutes of latitude and every 2° of longitude.