2. The mark shall:—
(a)be in the form specified in paragraph 3 below;
(b)conform with the test of durability specified in sub-clause 7.14 of British Standard 5850 (1981);
(c)be placed upon such apparatus in such a manner that it cannot easily be removed; and
(d)be so placed that it is on an outside surface of such apparatus where it is legible and readily accessible.