(1) Subject to sections 18, 20 and 22, if the tariff classification under which goods are classified contains 2 or more phrases that describe goods and begin with the words "In respect of'', the duty payable in respect of the first - mentioned goods is:
(a) if the first - mentioned goods have as constituents goods to which 2 or more of the phrases relate--the sum of the amounts of the duty, worked out in accordance with subsection (3), in respect of each of the goods to which those phrases respectively relate; or
(b) if the first - mentioned goods are, or have as constituents, goods to which only one phrase relates--the amount of duty, worked out in accordance with subsection (3), in respect of the goods to which that phrase relates.
(2) If the words "In respect of remainder" appear in a tariff classification under which goods are classified, those words constitute a phrase for the purposes of this section and the word "remainder" appearing in that phrase must be taken to be a description of:
(a) all goods that can be constituents of goods that can be classified under the tariff classification; and
(b) all goods that can be classified under the tariff classification;
other than goods to which another phrase contained in that tariff classification relates.
(3) The duty in respect of constituent goods to which a phrase referred to in subsection (1) relates worked out in accordance with section 17 must be worked out as if:
(a) the tariff classification under which the complete goods are classified were the tariff classification that contained that phrase; and
(b) the rate of duty or rates of duty specified in the third column of that tariff classification in relation to the constituent goods to which that phrase relates were the only rate or rates set out in that tariff classification.