Page "Natural Area Code" Paragraph 1

Instead of numerical longitudes and latitudes, a grid with 30 rows and 30 columns-each cell denoted by the numbers 0-9 and the twenty consonants of the Latin alphabet-is laid over the flattened globe.

A NAC cell ( or block ) can be subdivided repeatedly into smaller NAC grids to yield an arbitrarily small area, subject to the ± 1 m limitations of the World Geodetic System ( WGS ) data of 1984.