[Therion] grid on elevation map

[Gilbert Fernandes (mailinglist)]

hello,

I try to put a grid on my survey, I set the grids instructions in the 
thconfig file

   grid-size 50 50 50 m
   grid top

it's work find for the map, but on the elevation map, Therion generate 
grid lines outside the survey.
Explanation : my cave elavation go from level 0 to -208. I have the grid 
lines for level 0, -50, -100, -150, -200 and it's fine. But I have also 
the grid lines for level +50 and -250. So my PDF doc is very high.
How can I suppress these 2 grid lines.
On the map I do not have the problem, grid cross are "inside" the map 
rectangle, not outside.

Thanks,

Gilbert