title "Fill area between two curves (above/below)"
xrange 250:500
yrange 5:30
no-xlabel
no-ylabel
region /color=Red /reversed-color=Green
legend-inside tr
plot 'silver.dat' /legend=Curve1 /color=Black
plot 'silver.dat'@'$1:$3+$1/50' /legend=Curve2 /color=Blue