Define symbol statements. SYMBOL statements define the characteristics of the lines and labels for the contour lines. Each SYMBOL statement is associated to an individual contour level starting with the first level displayed in the LEGEND.

symbol1 value="DEEP"
        color=red
        font="Arial Rounded MT Bold"
        height=.6;
symbol2 color=green
        height=.45;
symbol3 color=blue
        height=.45;
symbol4 color=orange
        height=.45;
symbol5 color=purple
        height=.45;
symbol6 color=magenta 
        height=.45;
symbol7 value="Shallow"
        color=navy 
        font="Arial Rounded MT Bold" 
        height=.7;