tcl_output of a list of lists prints SIMP or NIL before the values
A #rrggbb color with a bad last digit, such as "#00000g", is accepted
The documented keyword ztics is rejected as unknown
nognuplot_svg_background has no effect
[xlabel,5] gives a Lisp error and [ylabel,abc] writes invalid gnuplot
The documented plot option nocolor_bar_tics is rejected as unknown
plot2d with logy warns that values will be clipped when none are
hue, saturation and value palettes are not checked; a bad one gives a Lisp error when plotting