4.—(1) The rates of penalty charges imposed by a charging scheme shall be specified in the scheme.
(2) Different rates of penalty charges may be specified for–
(a)different classes of penalty charge;
(b)different times;
(c)different times of day;
(d)different parts of a charging area;
(e)different distances travelled;
(f)different classes of vehicles; or
(g)different circumstances in which penalty charges are imposed.