Define pattern colors. Each value of the
chart variable ENGYTYPE is assigned a pattern whether or not it is displayed
as a separate slice. Patterns are assigned to midpoints in the order the values
appear in the data set. Because ENGYTYPE is character, the patterns are assigned
alphabetically. The eighth pattern is for the "other" slice, which is always
last.
pattern1 color=black; /* biofuels */
pattern2 color=blue; /* coal */
pattern3 color=green; /* gas */
pattern4 color=gray; /* geothermal */
pattern5 color=lipk; /* hydroelectric */
pattern6 color=lime; /* nuclear */
pattern7 color=cyan; /* petro */
pattern8 color=red; /* other */