"NOAA's National Geodetic Survey (NGS) defines and manages a national coordinate system. This network, the National Spatial Reference System, provides the foundation for transportation and communication; mapping and charting; and a multitude of scientific and engineering applications." The NGS Web site contains several helpful resources for researchers and professionals including a monthly newsletter, aeronautical data, GPS data, datasheets, a geodetic tool kit, software, and much more. The datasheets for example, are ASCII text files that contain data for survey control stations maintained by NGS that show precise latitude and longitude as well as orthometric heights or elevations. Other available data include geoid height, state plane coordinates, and Universal Transverse Mercator coordinates. [JAB]