The Hypsography DLG attribute information includes multiple files. There is a DBF file (dBASE version III - 100hypso.dbf), a Word file (100hpupd.doc) both with attribute information concerning hypsography (basically contour information).

The DBF file was derived from several text files, as was the Word file; where information is duplicated in both files it will be identical. The Word file, however, contains more information than DBF file. This is due mostly to the nature of the data and a database. The DLG data when imported has major and minor codes, all classified as numerals. The text documentation had a mixture of text and numerals in the attribute code columns. This did not translate perfectly into a database format that could be used as a lookup table.

The original files documenting this data came from the U.S. Geologic Survey (USGS), as text files. There were two sets of files; the original documentation, and an updated version from 1995. The more recent documents are available on this site as well, in a zipped version. The files includes here are a combination of the new and old files. The DBF file contains ONLY the current (new) codes. The Word file contains the current data as well as notations on the older codes. BE AWARE that DLG data on the WWW may be new or old vintage, and may have old as well as new coding. With these two files you should be able to resolve conflicts over unclear codes.

In some cases the text description could be transformed into numerals; where this was fairly easy to do, such as the major code (feet, meters, etc) for hydrography, water surface elevation, numerals were inserted into the DBF file. In all other cases, a 999 (for major codes) or 9999 (for minor codes) has been inserted into the location in the file where the text values were. The original values have been moved to the BEGINNING of the description field, and placed in parens (). This is the case for a number of the hypsography elevation codes.

For the Hypsography data, the 100hypso.dbf file fields are labeled major1, minor1, and description. There are actually more fields than this in the DLG file; major1, minor1, major2, minor2, major3, minor3, and description in the ones checked. The DBF file can be used as a lookup for any of the major/minor combinations, as the codes are the same in each case. In the sample files checked, the major1/minor1 fields indicated that the line was a contour, and the major2/minor2 field (with few exceptions) indicated the elevation in meters.

The assumption has been made with these files that if you are importing the DLG data into ArcView (and probably into Arc/Info as well, although that is yet to be tested) you will import the hypsography information as a line file. The only information that showed when the data was imported as a polygon file was a polygon ID number (no major or minor codes). These polygons did match with the lines, and could possibly be used in area calculations or to convert to a grid file.