Gziped files contains:

sloangroups0.dat and sloangroupsF.dat: Groups information. 
sloangroups0.dat correspond to the first identification.
sloangroupsF.dat correspond to the improved catalog.

 1 group number
 2 center of mass right ascention [degrees]
 3 center of mass declination [degrees]
 4 center of mass radial velocity [km/s]
 5 velocity dispersion [km/s]
 6 virial mass [Msun h^{-1}]
 7 number of members
 8 virial radius  [Mpc h^{-1}]
 9 status (only in sloangroupsF.dat: RC=recentered group)

sloangal-in-groups0.dat and sloangal-in-groupsF.dat: 
Galaxies in groups information.

 1 right ascention [degrees]
 2 declination [degrees]
 3 number of members in the corresponding group
 4 redshift
 5 group number
 6 r apparent magnitude
 7 ecoeff spectral type
 8 sloan release original fits file
 9 line number in the original fits file