Commission Regulation (EEC) No 3820/81 of 23 December 1981 derogating in respect of the countries which have signed the Cartagena Agreement (Andean Group) from Articles 1, 6 and 12 of Regulation (EEC) No 3817/81 on the definition of the concept of originating products for purposes of the application of tariff preferences granted by the European Economic Community in respect of certain products from developing countries