Note: As of November 2001 we are not using the standard scrip1.4
version of convertPOPT, but have nonstandard code to use the
ccsm_pop/cice calculation of T-grid cell center locations, and we use
Keith's nonstd calculation of southern-most points. I'm getting this
code from 
  /fs/cgd/home0/hecht/csm/fortran/SCRIP/scrip1.4/grids/convertPOPT.f
This file is under revision control, in 
  /home/hecht/my_cvs/SCRIP/scrip1.4/grids/convertPOPT.f,v
Note also that there was a (harmless, it seems) bug in this nonstandard 
version of convertPOPT.f, affecting the grid coordinates in the (unused)
j=1 row. This is why these maps are being regenerated today. The diffs
between buggy -r1.3 code and bug-fixed code are:
*** 306,313 ****
        n = 0
        do i=1,nx
           n   = n + 1
!          np1 = n + ny
!          np2 = n + 2*ny
           grid_center_lon(n) = grid_center_lon(np1)
           grid_center_lat(n) = 2.0*grid_center_lat(np1) - 
       $        grid_center_lat(np2)
--- 306,313 ----
        n = 0
        do i=1,nx
           n   = n + 1
!          np1 = n + nx
!          np2 = n + 2*nx
           grid_center_lon(n) = grid_center_lon(np1)
           grid_center_lat(n) = 2.0*grid_center_lat(np1) - 
       $        grid_center_lat(np2)
---

In grids subdir,
produce gx3v2_020225.nc from:

   convertPOPT

Add documentation:

   ncatted -O -h -a Created_by,global,a,c,"`whoami`, `date`" gx3v2_020225.nc
   ncatted -O -h -a 1D_grid_indexing,global,a,c,"if n is 1D index, i runs fast, j runs slow: n=(j-1)*fast_grid_dim+i" gx3v2_020225.nc