art 6 Ear tags
(1) No person shall attach an identification mark to a pig in the form of an ear tag unless the ear tag satisfies the provisions of paragraph (2); and in this Order references to an ear tag are to an ear tag which satisfies those provisions. (2) An ear tag shall be so constructed as— (a) not adversely to affect the well-being of the pig to which it is attached; (b) to be incapable of being altered in such a way that the fact of alteration cannot be readily observed; and (c) to be incapable of re-use.