unset border
unset tics
unset key
H = 1.0
RN = 26
set xrange [-2:50]
set term png enh font "/usr/X11R7/lib/fonts/TTF/arial.ttf,8" \
    size 480,480 
set out "marks_png.png"
set origin 0,0
plot for [ i= 0:10] for [j = 0:RN-1] '+' u (5*i):(H*(RN-j))  ps 1.2,\
     for [ i = 0:10] for [j = 0:RN-1] \
          '+' u (5*i-2):(H*(RN-j)):(sprintf("%d",RN*i+j+1)) w labels

# png の記号は 93*13 = 1209 種類
# 色が 93 種類の循環
# 形が 13 種類の循環