art 23 Replacement of an identification mark
(1) A keeper must replace an identification mark if it has— (a) become illegible; (b) been removed for welfare reasons; or (c) been lost. (2) Any person replacing an identification mark must either— (a) apply an identical identification mark; or (b) apply a new identification mark and cross-refer the new identification mark with the original identification mark in the record kept under article 5.