/****************************************************************************
 *
 * MODULE:       dspf library
 * AUTHOR(S):    
 *               Originally by Bill Brown, with contributions from
 *               Bill Hughes, Brook Milligan, Helena Mitasova
 *               Started in GRASS 4.x with makedspf program, then
 *               appeared as this lib in GRASS 5.0beta_2i**. 
 *               Subsequent (post-CVS) contributors:
 *               Markus Neteler <neteler itc.it> 
 *               Glynn Clements <glynn gclements.plus.com>,
 *               Bernhard Reiter <bernhard intevation.de>
 * PURPOSE:      libraries for NVIZ: render/display volumes
 * COPYRIGHT:    (C) 1996-2006 by the GRASS Development Team
 *
 *               This program is free software under the GNU General Public
 *               License (>=v2). Read the file COPYING that comes with GRASS
 *               for details.
 *
 *****************************************************************************/

Info in .grid3 headers:
   version number
   xdim ydim zdim
   north south east west top bottom
   ns_res ew_res tb_res
   zone 
   proj 
   type (1=short 2=int 3=float)
   min max (data values)

Info in .dspf headers:
   version number
   xdim ydim zdim
   min max
   lightmodel (1=flat 2=gouraud)
   number of thresholds
   array of threshold values
   data offset 
   lookup offset

Thu Mar 28 09:31:59 CST 1996
In process of eliminating use of .grid3 files, using
new 3dgrid format instead.