This data set is referenced to Wisconsin Transverse Mercator, based on the North American Datum of 1983, 1991 adjustment. For more information, refer to: <http://www.dnr.state.wi.us/maps/gis/wtm8391.html>
The metadata for Digital Line Graphs is available through the USGS National Spatial Data Infrastructure (NSDI) Clearinghouse at: <http://edcwww.cr.usgs.gov/>
ARCEDIT commands were used, if needed, to correct topological errors and to ensure topological integrity. Various edgematching procedures were used to ensure topological fidelity along the 'seams' shared by adjacent coverages (these seams being artifacts of the DLG file structure).
The principal modification to the DLG feature attribute coding design was the creation of separate items for thematically distinct feature attributes. Thematically similar feature attributes were grouped together in the same items. The DLG major codes were dropped to avoid redundancy, but DLG minor codes were generally retained to accommodate users already familiar with the codes. New attributes of potential use were added to some coverages. An attribute identifying the largest polygon in each political of administrative unit was added to some coverages, to facilitate statistical summaries or labelling. For each coverage in which DNR/GEO modified or added DLG feature attribute codes during processing, a code was added to a new item named EDIT_FLAG to indicate a code update had occurred.
Following data verification, all coverages underwent spatial indexing (using the ArcInfo command INDEX) to reduce display times. Projection (.prj) files were added to each coverage to enable users to display coverage projection parameters by entering the DESCRIBE command. All coverages were then inserted into the DNR GIS Database statewide library structure (WISLIB).
In 1997, WISLIB data layers were projected from WTM based on NAD27 to WTM based on the 1991 adjustment to NAD83 (WTM83/91), and placed in the DNR GIS Database statewide library WISLIB91. The open water line shapefile was generated in 1998.