not necessarily spaced evenly around the color wheel. For example,
blue_green, green, and light_yellow looks better than red, green, blue.
.PP
-Certain graph attributes control the \fIgvcolorf\P algorithm.
+Certain graph attributes control the \fIgvcolor\fP algorithm.
\fBflow=back\fP reverses the flow of colors from heads to tails.
\fBsaturation=.1,.9\fP (or any two numbers between 0 and 1)
adjusts the color saturation linearly from least to greatest rank.