All coverages contain the standardized attributes for arcs and polygons assigned by ARC/INFO.  For arcs these attributes are:
>COLUMN--ITEM_NAME----------WIDTH-----OUTPUT-----TYPE---#_DECIMALS
>1-------FNODE#---------------4----------5---------B---------\
>5-------TNODE#---------------4----------5---------B---------\
>9-------LPOLY#---------------4----------5---------B---------\
>13------RPOLY#---------------4----------5---------B---------\
>17------LENGTH---------------8---------18---------F---------5
>25------<cover>#-------------4----------5---------B---------\
>29------<cover>-ID-----------4----------5---------B---------\
For polygons these attributes are:
>COLUMN--ITEM_NAME----------WIDTH-----OUTPUT-----TYPE---#_DECIMALS
>1-------AREA-----------------8---------18---------F---------5
>9-------PERIMETER------------8---------18---------F---------5
>17------<cover>#-------------4----------5---------B---------\
>21------<cover>-ID-----------4----------5---------B---------\
>****The following coverages were used in both Map A and Map B****
>COVERAGE--------ENTITIES---------DESCRIPTION
>dvrfspoly-------lines/polygons---base map
>halo_bd---------lines------------flow model boundary
>hstruc2---------lines------------faults; attributed with ITEM h_code as follows:
>ITEM: h_code           DESCRIPTION              SYMBOL
>      1                Normal fault             1 (color.lin)
>      2                Strike-slip fault        2 (color.lin)
>      3                Detachment fault         83 (geoscamp1.lin)
>      4                Caldera Boundary         83 (geoscamp1.lin)
>      5                Transverse fault         5 (color.lin)
>      6                Thrust fault             27 (geology.lin)
>      7                Thrust fault (inferred)  37 (geology.lin)
>hydrostruc_bb---lines------------displacement symbols on faults
>dvrfs_rd--------lines------------roads (minor and major)
>dvrfs_hptxt-----points-----------text labels for physiographic features,
>                                   including town names.
>county_100k-----lines------------county boundaries
>nts_outline-----lines------------boundary of Nevada Test Site
>nvca------------lines------------State line boundary between California
>                                   and Nevada.
>stipplebuffer---polygons---------stippled area on faults that have
>                                   measurable late Pleistocene or younger
>                                   displacement.
>townpts---------points-----------locations of towns
>pot_cont--------lines------------potentiometric contours with elevations
>                                   posted on each contour line.
>cald_txt--------points-----------text lables for calderas
>flt_txt---------points-----------text lables for faults
>****The following coverages are used on Map A only****
>hueb, satb, valb-----------------color shaded-relief map, composited from
>                                   83-m DEM data from the following USGS
>                                   1:250,000-scale quadrangles:  Tonapah,
>                                   Lund, Las Vegas, Death Valley,
>                                   Caliente, Goldfield, Kingman, and Trona
>                                   and include depth to pre-Tertiary
>                                   surface.
>coldsprgs-------points-----------locations of cold springs
>springreg-------points-----------locations of regional springs (24 degrees
>                                   C to 35 degrees C).
>****The following coverages are used on Map B only****
>red, green, blue-----------------color shaded-relief map, composited from
>                                   83-m DEM data from the following USGS
>                                   1:250,000-scale quadrangles: Tonapah,
>                                   Lund, Las Vegas, Death Valley,
>                                   Caliente, Goldfield, Kingman, and
>                                   Trona.
>polybuffer------polygons---------zones that have special geologic
>                                   characteristics, as well as seismicity
>                                   clusters, that may be consistent with
>                                   relatively large hydraulic
>                                   conductivities.
>polynums--------points-----------roman numeral values used to label the
>                                   "polybuffer" cover.
>eq78to86--------points-----------earthquake epicenter locations.  Four (4)
>                                   ITEMS from this cover were used:
>                                   magnitude, date, x-coord and y-coord.
>                                   The date values that fell in the range
>                                   of 1978 to 1986 were used for this map.

http://pubs.usgs.gov/mf/2002/mf-2372/mf-2372_pam.pdf