19. Regulations may make provision (including provision modifying any provision of this Act) for cases—
(a)where the holder of a restricted licence makes an application under section 16(1)(j) to the Department to vary the licence by directing that it be converted into a standard licence; and
(b)where the holder of a standard licence which covers only national transport operations makes an application under section 16(1)(k) to the Department for a direction that the licence be varied to cover both national and international transport operations.