Excise duty exemption for synthetic tow consumed in manufacture of staple fibres during specified period; duty need not be paid. The Government identified a prevailing practice under which the duty of excise on synthetic tow (heading 55.01) consumed in the manufacture of staple fibres and tops was not levied during 28 February 1986 to 31 May 1988, and directed that the whole of the duty which would otherwise have been payable on such synthetic tow shall not be required to be paid in respect of cases where duty was not levied in accordance with that practice.