This set of files contains information about the gnuplot-PostScript interface.

ps_file.doc
  is a discussion of a PostScript file as written by gnuplot.

ps_guide.ps
  is a PostScript file that has two pages.  The first is a summary of the
  enhanced syntax (available via "set terminal postscript enhanced".  The
  second is a table of the character codes.  The table has the standard
  encoding (shown in Times-Roman), the Symbol and Zapf-Dingbats fonts, and
  the ISO-Latin1 (also known as ISO-8859-1) encoding.  The last entry may
  be changed to CP850 (for OS/2) or CP437 (for MS-DOS) by editing line #14
  in the file.  These non-standard encodings are selected via the "set
  encoding" command.

ps_symbols.gpi
  is a gnuplot command file that generates ps_symbols. ps.ps_symbols.ps
  is a PostScript file that shows a simple display of the 76 symbol types
  available to the "postscript" terminal and selectable via the "pt" option
  on the "plot" command.