1 . TAX PROVISIONS - HARMONIZATION OF LEGISLATION - TURNOVER TAXES - COMMON SYSTEM OF VALUE-ADDED TAX - SIXTH DIRECTIVE - TERRITORIAL SCOPE - TAXATION BY A MEMBER STATE OF SERVICES PERFORMED OUTSIDE ITS SOVEREIGN TERRITORY ON BOARD A VESSEL OVER WHICH IT HAS JURISDICTION - ADMISSIBILITY ( COUNCIL DIRECTIVE 77/388 , ARTS 3 AND 9 ) 2 . TAX PROVISIONS - HARMONIZATION OF LEGISLATION - TURNOVER TAXES - COMMON SYSTEM OF VALUE-ADDED TAX - SUPPLY OF SERVICES - DETERMINATION OF THE POINT OF REFERENCE FOR TAX PURPOSES - OPTIONS AVAILABLE TO THE MEMBER STATES - CRITERION - APPROPRIATENESS FOR TAX PURPOSES ( COUNCIL DIRECTIVE 77/388 , ART . 9 ( 1 )) 3 . TAX PROVISIONS - HARMONIZATION OF LEGISLATION - TURNOVER TAXES - COMMON SYSTEM OF VALUE-ADDED TAX - SUPPLY OF SERVICES - DETERMINATION OF THE POINT OF REFERENCE FOR TAX PURPOSES - ' FIXED ESTABLISHMENT ' WITHIN THE MEANING OF THE SIXTH DIRECTIVE - CONCEPT - OPERATION OF GAMING MACHINES ON BOARD A VESSEL ON THE HIGH SEAS ( COUNCIL DIRECTIVE 77/388 , ART . 9 ( 1 )) 4 . TAX PROVISIONS - HARMONIZATION OF LEGISLATION - TURNOVER TAXES - COMMON SYSTEM OF VALUE-ADDED TAX - EXEMPTIONS PROVIDED FOR IN THE SIXTH DIRECTIVE - EXEMPTION OF SERVICES TO MEET THE DIRECT NEEDS OF SEA-GOING VESSELS - OPERATION OF GAMING MACHINES INSTALLED ON BOARD - EXCLUSION ( COUNCIL DIRECTIVE 77/388 , ART . 15 ( 8 ))