from NERSL CD-ROM text file, see Open File Report 92-289

                            TECHNICAL DOCUMENTATION


       The SEISMIC directory contains files in a format that optimizes
       data display and manipulation for program  SEGMENT.    The .VAL
       files which have the modified  SEG-Y  data are not available on
       this CD-ROM due to space  limitation  however the summary files
       allow  the  user  to  preview  the  seismic lines to show their 
       relationship to the GLORIA  and the GEOLOGY basemaps.  The file
       types are as follows:

        .RMS          These files contain the  root-mean-square calcula-
                      tions for each trace in the line.   These are  the 
                      data that  get plotted  in the  "Extended  Seismic 
                      Section Plot".

        .VPT          These files contain EGA/VGA summary plots for each
                      line which  are used in the plots of "Full Seismic
                      Section" on EGA/VGA terminals.

        .XPT          These files contain extended VGA summary plots for
                      each  line  which  are  used in the plots of "Full 
                      Seismic Section"  on extended VGA terminals.

        .MAP          These  are   individual   map   files   used   for 
                      highlighting individual lines.

        .SPN          These files contain side-panel information that is
                      ordinarily  displayed  with  paper  copies  of the
                      seismic data.

        .LBL          These  files contain information that is needed to
                      plot and reconstruct the SEG-Y data, such as block 
                      size and number of traces.

        .HDR          These  files contain all of the header information
                      from the  SEG-Y format.   This includes  the first 
                      3600 bytes  of the file and the first 240 bytes of 
                      each trace block.

        .NAV          These files contain the navigation records for the
                      shot points for each seismic line.