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<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 line elements. <br /> <br />Seven types of records are considered data records: <br /> <br />. Node and area identification records <br />. Node-to-line linkage records <br />. Area-to-line linkage records <br />. Line identif:,cation records (also contains line-to-node and line-to-area <br />linkages) <br />. Coordinate s1:ring records <br />. Attribute code records <br />. Text records (not currently used) <br /> <br />Appendix G, taken from USGS' Standards for <br />contents for DLG files in optional format. <br />data record specif:~cations. <br /> <br />Digital Line Graphs lists the record <br />Refer to this listing for additional <br /> <br />Outside Area <br /> <br />Each DLG provides s, coherent description of that portion of the eard! s sur'face <br />covered by a l:24,OOO-scale, 7.S-minute cell. To maintain topoloE;ical <br />consistency and to facilitate the combination (integration) of multipl,e 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 each 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 codes <br />of 0 are seen as invalid attribute codes for all features wi thin the DLG cell. <br /> <br />10/93 <br /> <br />10 <br />