TRANSPORT - ROAD TRANSPORT - SOCIAL LEGISLATION - DEROGATIONS - SPECIALIZED VEHICLES FOR DOOR-TO-DOOR SELLING - CONCEPTS OF ' ' SPECIALIZED VEHICLE ' ' AND ' ' DOOR-TO-DOOR SELLING ' ' ( REGULATION NO 543/69 OF THE COUNCIL , ART . 14A ( 3 ) ( A ), AS AMENDED BY REGULATIONS NOS 515/72 AND 2827/77 )