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| File Naming Convention For Delaware DLGs and DRGs |
Data files archived on this server are in WinZip format ending with the extension ".zip". The beginning part of the file name denotes the USGS quad ID and the format of the included data files. For example, if you wanted NEWARK WEST quad data in DLG standard format, the file you would be downloading is named:
f739075_dd.zip
where,The five possible data file formats available through this web site are:
- "f739075" represents the USGS quad ID for NEWARK WEST, namely 39075-F7
- "_dd" represents the format of the included data files, namely DLG standard
- ".zip" represents the format of this file, namely WinZip format
_dd DLG standard _do DLG optional _ai Arc/Info export _av ArcView shapefile _tf TIFF
Each zip file contains several individual data files. The beginning of each file denotes quad and type (layer) of the data, whereas the extension denotes the data file format. File extensions have the following types:Special Notes
.dd DLG standard .do DLG optional .e00 Arc/Info export .shp, .shx, .dbf ArcView shapefile .tif TIFF .tfw World/Projection file for DRG image .cns Metadata file created by RDMS
DLG data are comprised of 9 layers (as opposed to DRG data: one .tif image file, one .tfw world file, and one .fgd metadata file). Layer abbreviations and topology are as follows:
bd Boundary Polygon/Line hy Hydrography Polygon/Line ms Manmade Features Polygon mt Pipe and Trans Lines Line n0/hyp Hypsography Line nv Non-Vegetative Features Line rd Roads and Trails Line rr Railroads Polygon/Line sc Vegetative Surface Cover Polygon
Layers that are labeled "Polygon/Line" have two sets of files when in ArcView shapefile format; this is because shapefiles cannot have more than one type of topology. File with an "a" at the end of the file name are the line shapefiles, files without the "a" are the polygon shapefiles.
The quad identification is noted by either the USGS ID (e.g., the USGS ID for NEWARK WEST is 39075-F7; here is a list of all DE quads and their USGS IDs) or by a filelist ID numbering from 1 to 54 (there are 54 quads in Delaware.) The link between the filelist ID and the quad name can be found in the DLG readme file that came with the CD-ROM.
Hypsography data files in Arc/Info export format may vary in the naming convention employed, though each file should be easily distinguishable.
Quads WEST GROVE, 39075-G7 in New Castle County and SUDLERSVILLE, 39075-B7 in Kent County do not have hypsography data due to their small spatial coverage of Delaware.