This field is a code to indicate which sets of coordinates available to BMFM are presumed to be the most accurate, the latitude and longitude or LORAN. It represents how these more accurate coordinates were generated, if known. Values are;
DGPS: these latitude and longitude coordinates were taken with a DGPS unit on the reef,
GPS: these latitude and longitude coordinates were taken with a non-differential GPS unit on the reef,
LOR: these LORAN coordinates were taken by LORAN unit on the reef,
BOTH: Both sets of coordinates were given to BMFM
If blank, it is unknown how these coordinates were generated and which sets are most accurate. LORAN is assumed to be more accurate prior to about 1995. Andren Software using ASFs from the 1984 Defense Mapping Agency tables mathematically calculated most of the non-field generated coordinates using the LORANGPS software.
Please note that all coordinates used to create the shapefile were the latitude and longitude coordinates.