The DLG features produced by the generated mapping file consist of geometry and explicit attribute information.
Each feature that has passed through all of the factories in the generated mapping file has its feature type set to one of the following: HP, HY, SC, NV, BD, SM, RD, RR, MT, MS, or PL.
These features correspond to the category abbreviations as outlined in the DLG standards – see DLG Categories. The geometry of each feature is appropriate to the dlg_type: dlg_point features have a single coordinate pair, dlg_line features contain multiple coordinates, and dlg_area features define closed polygons with holes where appropriate.
DLG Categories
|
Name in Full |
Abbreviation |
|
Hypsography |
HP |
|
Hydrography |
HY |
|
Vegetative Surface Cover |
SC |
|
Non-Vegetative Features |
NV |
|
Boundaries |
BD |
|
Survey Control and Markers |
SM |
|
Roads and Trails |
RD |
|
Railroads |
RR |
|
Pipelines, Transmission Lines, and |
MT |
|
Man-made Features |
MS |
|
U.S. Public Land Survey System |
PL |
|
Wetlands |
WL |
|
Unrecognized Category |
UNKNOWN |
All features share several attributes however, the feature will contain additional feature coding specific to the feature type. These are described in subsequent sections. All features tagged with major and minor codes of zero, indicating an outside area, are deleted.