set cmark marktype
Set the style of the marker for line plots, or for the gxout option 'stnmark'.
marktype may be one of the following:
0 - none 1 - plus sign 2 - open circle (default) 3 - closed circle 4 - open square 5 - closed square 6 - multiplication sign 7 - open diamond 8 - open triangle 9 - closed triangle 10 - open circle with vertical bar 11 - closed circle with vertical bar 12 - closed diamond (GrADS version 2.1+)
Here is a short script sample that draws all the mark types, followed by the image output after running the script.
m=1 while (m<=12) 'draw mark 'm' 'm/2' 5.5 0.2' 'set string 1 c ' 'draw string 'm/2' 5 'm m=m+1 endwhile