SUBROUTINE GRID

 GRID plots a  Cartesian grid or solid lines or ticks at grid intersections. See also LGRID.

CALL GRID (x,y,dx,dy,nx,ny)

x,y   (R): coordinates in the bottom left corner of grid
dx,dy (R): spacing of grid lines in x and y directions
nx,ny (I): number of grids in x and y direction
           if nx > 0 and ny > 0 then solid grid plotted
           if nx < 0  or ny < 0 then tick grid plotted
           if nx < 0 and ny < 0 then boxed tick grid plotted