Within the EU, livestock ear tags are required to conform to international technical standards, including the International Organisation for Standardisation (ISO) standards for identification codes.
O fewn yr UE, rhaid i dagiau clust da byw gydymffurfio â safonau technegol rhyngwladol, gan gynnwys safonau'r Sefydliad Safoni Rhyngwladol (ISO) ar gyfer codau adnabod.