mechanical pulp and weighing not less than 25 g/ m2 . Each licence or certificate of origin .part shall have a printed guilloche-pattern backgroundmaking any falsification by mechanical or chemical pieansapparent to the eye: TITLE VIf the documents have several copies only the top copy whichis the original shall be printed with the guilloche pattern ADMINISTRATIVE COOPERATIONbackground. This copy shall be clearly marked as 'original'and the other copies as 'copy'. Only the original shall beaccepted by the competent authorities in the Community as Article 17being valid for the purpose of export to the Communityin accordance with the arrangements established by the The Community and the USSR shall cooperate closely toAgreement. implement the provisions of the Agreement . To this end , contacts and exchanges of views ( including on technical2. Each document shall bear a standardized serial matters) shall be facilitated by the Contracting Parties .number , whether or not printed , by which it can beidentified . Article 18This number shall be composed of the following elements: In order to ensure the proper application of the Agreement,— two letters identifying the USSR as follows : SU , the Community and the USSR shall assist each other in checking the authenticity and accuracy of export licences and— two letters identifying Member State of destination as certificates of origin issued or declaration made under this follows : Protocol . BL Benelux , DK Denmark,