object Color
    components: r:RedIntensity and g:GreenIntensity and b:BlueIntensity;
    description: (*
        This definition of color defines a general-purpose abstract
        representation using the RGB style.  This use of RGB as an abstract
        specification does not imply that an implementation must use RGB as the
        underlying concrete representation of color.
    *);
end;

object RedIntensity = integer
    description: (* The red intensity value in a RGB-style color. *);
end;

object GreenIntensity = integer
    description: (* The green intensity value in a RGB-style color. *);
end;

object BlueIntensity = integer
    description: (* The blue intensity value in a RGB-style color. *);
end;

axiom ColorIntensityConstraints is
    forall (c: Color)
	c.r >= 0 and c.r <= 255 and
	c.g >= 0 and c.g <= 255 and
	c.b >= 0 and c.b <= 255;