ECSC - PRODUCTION - STEEL PRODUCTION QUOTA SYSTEM - UNDERTAKINGS REFERRED TO - GROUP OF CONCENTRATED UNDERTAKINGS - CONCEPT - REFERENCE TO ARTICLE 66 OF THE TREATY - WHETHER PERMISSIBLE - ENTITY TO WHICH QUOTAS TO BE ALLOCATED - UNDERTAKING WHICH DIRECTS GROUP ' S PRODUCTION ACTIVITIES ( ECSC TREATY , ARTS . 58 , 66 AND 80 ; GENERAL DECISION NO 1696/82 , ART . 2 ( 4 ))