# set terminal canvas  solid rounded size 600,400 fsize 10 lw 1.6 fontscale 1 name "contours_4" jsdir "."
# set output 'contours.4.js'
set key at screen 1, 0.9, 0 right top vertical Right noreverse enhanced autotitles nobox
set view 60, 30, 0.85, 1.1
set samples 20, 20
set isosamples 21, 21
set contour base
set cntrlabel  format '%8.3g' font '' start 5 interval 20
set cntrparam levels discrete -75,-50 ,0 
set style data lines
set title "discrete set of contours (at -75, -50, 0)" 
set xlabel "X axis" 
set ylabel "Y axis" 
set zlabel "Z " 
set zlabel  offset character 1, 0, 0 font "" textcolor lt -1 norotate
set fit brief noerrorvariables errorscaling noprescale nowrap
splot x*y