COLOUR

colours

 If no parameter is entered, a list of the colour names and
 corresponding colour numbers is displayed.  You may then enter a
 colour name or a colour  number.

 colour names   n
 -----------------
  black         0
  white         1
  red           2
  green         3
  blue          4
  yellow        5
  cyan          6
  magenta       7
  white         8

pen_plotters

 For pen plotters, the colour of the pens should be confirmed before
 submitting a plot file to a plotter.

SCALAR

 If a variable is to be used for the colour number, it must have the
 qualifier \SCALAR attached to it.  For example:

 COLR=5
 COLOUR COLR\SCALAR