15.58.4  CYCLE 

When plotting more than 1 data set, CYCLE causes the line symbol, texture,
color, and width to vary from one plot to the next.  The  cycle  table  is
set  by  the  SET  CYCLE  command.   If  you have specified either symbol,
texture, color or width it overrides the cycle values.

When doing a scatter plot of a mesh, CYCLE causes the symbol,  line  color
and width to vary according to the cycle table.

When  plotting  a  mesh table the color and width of each number will vary
according to the CYCLE TABLE.