AGRICULTURE - COMMON ORGANIZATION OF THE MARKETS - MILK PRODUCTS - CHEESE OF SHEEP ' S MILK - IMPORTATION FROM THIRD COUNTRIES - LEVY - FIXING - DETAILED RULES - SPECIAL SYSTEM OF ARTICLE 8 OF REGULATION NO 823/68 - PREFERENTIAL TREATMENT - IMPORTER - ABSENCE OF VESTED INTEREST - NEEDS OF THE COMMON ORGANIZATION OF THE MARKETS AND THE COMMON COMMERCIAL POLICY - FREEDOM OF ACTION ON THE PART OF THE COMMUNITY