(a) if the article is ordinarily sold by number—by reference to number;
(b) if the article is ordinarily sold by linear or superficial measurement —by reference to that kind of measurement;
(c) if the article is a liquid—by reference to volume;
(d) if the article is solid (including in the form of powder or flakes), semi-solid or partly solid and partly liquid, and is not included in paragraph (a)—by reference to mass.
(2) The measurement marking of an article of a kind described in Column 1 of Schedule 2 must be expressed by reference to the kind of measurement specified in Column 2 of that Schedule opposite the description of the article.
(3) A measurement marking (other than in terms of number) must be expressed in terms of a permissible unit of measurement specified in Schedule 3.