Prior to digitizing each base map must be initialized to orient the map and relate it in geographic coordinates to the surface of the earth. The person responsible for digital data entry completes a data sheet describing coverage name, date of entry, and whether a topology for the coverage is established. This function creates unique identities for each polygon. Next each base map is tested for polygon errors through an internal editing function. Errors are corrected for unlabeled polygons, unclosed polygons, or polygons with more than one label.
Topology is reestablished for each coverage and tested again until no error are indicated.
The digital coverage is then plotted at the same scale as the original base map. This coverage is overlaid on a light table with the original and visually inspected for replication of original lines with digitized lines. Two individuals independently inspect the coverage The national coverage was projected to Region 8 Albers and clipped with region 8 states coverage. Updated lines in Montana from revised level IV lines. Revised lines were reviewed by Sandy Bryce, Dynamac 6.