The accuracy of most attributes has not been explicitly tested against independent sources. However, all the data derived from the ArcUSA database have been reviewed for anomalous visual patterns both on line and in hard copy. Item values are compared against a series of user-specified conditions to identify illogical code combinations. All data were found to be topologically correct. No duplicate features are present.
All polygons are closed, and all lines intersect where intended.
No undershoots or overshoots are present. It defines polygon topology when the POLY option is used. Features may have been generalized or eliminated on the source graphic, due to scale and legibility constraints. The original DLG data met the criteria for inclusion in the National Digital Cartographic Database. Data Users Guide 3.