# set terminal svg size 600,400 dynamic enhanced fname 'arial'  fsize 10 mousing name "contours_6" butt solid 
# set output 'contours.6.svg'
set view 60, 30, 0.85, 1.1
set samples 20, 20
set isosamples 21, 21
set contour surface
set cntrparam levels auto 10
set title "3D gnuplot demo - contour plot on surface" 
set xlabel "X axis" 
set ylabel "Y axis" 
set zlabel "Z axis" 
set zlabel  offset character 1, 0, 0 font "" textcolor lt -1 norotate
splot x**2-y**2