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<br /> <br />DATA RECORD INFORMATION <br /> <br />In the optional DLG distribution format, topological linkages are explicitly <br />encoded for node and area elements as well as for li,ne elements. <br /> <br />Seven types of records are considered data records: <br /> <br />. <br /> <br />Node. &:1d. arei identification r-ecor-ds <br /> <br />. Node-to-line linkage records <br />. Area-to-line linkage records <br />. Line identification records (also contains line- to-node and line - to-area <br />linkages) <br />. Coordinate string records <br />. Attribute code records <br />. ~ext records (not currently used) <br /> <br />AppendiA G, taken from USGS' Standards for <br />content~ for DLG files in optional format. <br />data rec~rd specifications. <br /> <br />Dieital Line Grauhs lists the re"ord <br />Refer to this listing fOL addit: nal <br /> <br />Outside Area <br /> <br />Each DLG provides a coherent description of that portion of the earth's surface <br />covered by a 1:24,000-scale, 7.S-minute cell. To maintain topological <br />consistency and to facilitate the combination (integration) of multiple DLGs, the <br />area outside the cell is specifically identified for each DLG. This area <br />element, which must be the first area present in eacb data category, is assigned <br />a single attribute code with major and minor codes both equal to zero. <br /> <br />For all other features contained in the DLG for which no attribute code has been <br />explicitly defined, the attribute code records must be blank. Attribute coaes <br />of 0 are seen as invalid attribute codes for all features within the DLG cell. <br /> <br />10/93 <br /> <br />10 <br /> <br />