4.—(1) It shall be the duty of the packer or importer of packages to ensure that they are made up in such a way as to satisfy the following rules—
(a)the contents of the packages shall be not less on average than the nominal quantity;
(b)the proportion of packages having a negative error greater than the tolerable negative error shall be sufficiently small for batches of packages to satisfy the requirements specified in Schedule 2;
(c)no package shall have a negative error greater than twice the tolerable negative error.
(2) Compliance with the rules in paragraphs (1)(a) and (b) shall be determined by the reference test.