# Council Regulation (EC) No 21/2004 of 17 December 2003 establishing a system for the identification and registration of ovine and caprine animals and amending Regulation (EC) No 1782/2003 and Directives 92/102/EEC and 64/432/EEC, Division 3: The first means of identification referred to in Article 4(2)(a) must comply with the criteria set out in either point (a) or (b):

Extent: E+W+S+N.I.

(a)an electronic identifier in the form of a ruminal bolus or an electronic eartag, in accordance with the technical characteristics listed in point 6; or
(b)an eartag made of non-degradable material, which is tamper-proof and easy to read throughout the lifetime of the animal; it must be non-reusable and the codes referred to in point 2 must be non-removable.

---
Source: https://www.legislation.gov.uk/eur/2004/21/annex/division/A/division/3 (the official version)
Page: https://openlegislation.uk/eu-regulation-2004-21/annex/division-A/division-3
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.