CGM

CGM is the Computer Graphics Metafile standard. This ANSI/ISO standard
defines the format of a file that describes one or more two-dimensional
images.

A CGM metafile is not a picture. It only contains a description of the
picture. In order to see the picture, the information in the file must be
translated by another program like GPLOT for a specific output device. This
output device is most commonly either a Tektronix emulating terminal, or a
PostScript printer.

Three variants of the CGM format are available: binary, character, and clear
text. Binary is the most compressed and efficient. Character mode is more
portable over networks. Clear text mode is human-readable. The user can go
into a clear text CGM file and read the description, altering or adding to
it.

In general, binary is preferred, because it's so much smaller. While
efficient, this means that CGM file transfers must be done carefully. You'll
want to pay special attention to the instructions for transferring CGM files
found in the documentation for the VMS CRAY station (see the dispose
command), the ULTRIX pscsub command (see pscdispose), and the documentation
for using the ftp command in binary mode. In addition, a little extra
caution is needed when transferring CGM files created by NCARGKS.

Many of our applications packages include a graphics interface. In most
cases, we've modified the packages so that when graphics are requested, the
packages call DRAWCGM to produce CGM metafiles. Moreover, the graphics
packages that we support all create CGM files.

See also:

   * Sample CGM files.
   * Other graphics packages installed on PSC systems.
   * Reference:
        o Computer Graphics - Metafile for Storage and Transfer of Picture
          Description Information, ANSI Document X3.122-1986, ISO DIS 8632
          (1987)
        o The CGM standard, which includes CGM format information, is
          available from:
               ANSI Publications: 1430 Broadway; NY,NY 10018
               (212)642-4900

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Revised: Nov 25, 1993
URL: http://www.psc.edu/general/software/packages/cgm/cgm.html