The zipped file includes for each TIFF image internal GeoTIFF
georegistration, a MapInfo format table file (.tab), and an ESRI format world
file (.tfw). Separate files are provided for the quadrangle planimetric(map body) and topography(contours) layers.
DOT Edition Date: 1976
USGS Contour Date: 1988
Contour Interval: 6
Scan type: Film Scanned and Edgematched at 508 dpi resolution
USGS Digital Raster Graphic (DRG) Quadrangle
(1:25,000 scale - UTM Zone 18, NAD 27)
Publication Date: 1988
Note: If you download this file, you'll see that the file name doesn't begin with an o, like most other USGS files, but rather with a k, e.g. k42073f3.zip. The k indicates that the DRG actually covers two adjoining quadrangles.