unset border
unset tics
unset key
H = 1.0
RN = 13
set xrange [-2:36]
set term pngcairo enh font "/usr/X11R7/lib/fonts/TTF/arial.ttf,8" \
    size 480,360
set out "marks_cairo.png"
plot for [ i= 0:9] for [j = 0:RN-1] '+' u (4*i):(H*(RN-j))  ps 1.4,\
     for [ i = 0:9] for [j = 0:RN-1] \
     '+' u (4*i-1.6):(H*(RN-j)):(sprintf("%d",RN*i+j+1)) w labels

# pngcairo の記号は 9*13 = 117 種類
# 色が 9 種類の循環
# 形が 13 種類の循環