Intended use of data: These data are typically used as base data for other coverages, and should be used at scales of 1:500,000 and smaller. The data are intended for use as a general reference to the location of the pipelines and powerlines.
The 1:100,000-scale Digital Line Graph (DLG) data files are digital representations of cartographic information. Data files of topographic and planimetric map features are derived from cartographic source materials using manual and automated digitizing methods.
Attribute codes are used to describe the physical and cultural characteristics of DLG node, line, and area elements. The codes are based on cartographic features symbolized on source maps. Each DLG element has one or more attribute codes composed of a three-digit major code and a four-digit minor code.
Related spatial and tabular data sets: Rio Puerco Watershed Basin Boundary (wshed)
DLG attribute codes are checked by software against a table of valid codes to ensure that each attribute in a file is valid for the category and element type to which it is assigned. Validating the codes for correct application is currently a manual process involving the correlation of formatted listings with proof plots and graphic displays.
Accuracy of these digital data (if not digitally revised), is based upon the use of source graphics which are compiled to meet National Map Accuracy Standards. NMAS horizontal accuracy requires that at least 90 percent of points tested are within 1/50th of an inch of the true position. Comparison to the graphic source is used as control to asses digital positional accuracy. Cartographic offsets may be present on the graphic source, due to scale and legibilty constraints. For more information on National Map Accuracy Standards, refer to USGS Fact Sheet FS-078-96 (September 1997), or visit <URL:http://mapping.usgs.gov/mac/isb/pubs/factsheets/fs07896.html>.
Features other than pipelines and powerlines were permanently removed from the data set.
Some attributes in <covername>.aat, including fnode#, tnode#, lpoly#, rpoly#, length, cover#, and cover-id are included in the coverage by default. Please refer to ESRI's ARC/INFO documentation for more detailed descriptions of these attributes.
The 'major1' attribute contains a three-digit major DLG code.
The 'minor1' attribute contains a four-digit minor DLG code.
The 'major2' attribute contains a second three-digit major DLG code.
The 'minor2' attribute contains a second three-digit minor DLG code.
The 'major3' attribute contains a third three-digit major DLG code.
The 'minor3' attribute contains a third three-digit minor DLG code.
190: Transportation; Pipelines, Transmission Lines, Miscellaneous Transportation Features; 199: Parameter for Coincident Feature (Transportation; Pipelines, Transmission Lines, Miscellaneous Transportation Features;) 201: Pipeline; 202: Power Transmission Line; 203: Telephone or Telegraph Line; 205: Arbitrary Extension Closure Line; 17: Feature Coincident with Road;
For more information on major and minor DLG codes, please refer to: U.S. Geological Survey, 1989, Digital Line Graphs from 1:100,000-Scale Maps, Data User Guide 2: U.S. Geological Survey, 88 p.
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