RULE , CHARACTERIZED BY THEIR HIGH FINISH AND HIGH PRECISION . MOST OF THEM ARE USED MAINLY FOR SCIENTIFIC PURPOSES ( LABORATORY RESEARCH WORK , ANALYSIS , ASTRONOMY , ETC .), FOR SPECIALIZED TECHNICAL AND INDUSTRIAL PURPOSES ( MEASURING AND CHECKING , OBSERVATION , ETC .) OR FOR MEDICAL PURPOSES .
. . .
THERE ARE CERTAIN EXCEPTIONS TO THE GENERAL RULE THAT THE INSTRUMENTS AND APPARATUS FALLING WITHIN THIS CHAPTER ARE HIGH PRECISION TYPES . FOR EXAMPLE , THE CHAPTER ALSO COVERS ORDINARY GOGGLES ( HEADING 90.04 ), SIMPLE MAGNIFYING GLASSES AND NON-MAGNIFYING PERISCOPES ( HEADING 90.03 ), DIVIDED SCALES AND SCHOOL RULES ( HEADING 90.16 ) AND FANCY HYGROSCOPES IRRESPECTIVE OF THEIR ACCURACY ( HEADING 90.23 ) ' ' .
8 IT IS EVIDENT BOTH FROM THE WORDING OF TARIFF HEADING 90.18 AND FROM THE EXPLANATORY NOTES ABOVE THAT THE CRITERION OF SIMPLICITY CANNOT BE ADOPTED TO EXCLUDE AN APPLIANCE FROM CHAPTER 90 OF THE COMMON CUSTOMS TARIFF .
9 THIS CONCLUSION IS SUPPORTED BY A READING OF THE EXPLANATORY NOTES ON TARIFF HEADING 90.18 AS THEY EXISTED BEFORE OCTOBER 1979 , WHICH STATE THAT THAT HEADING COVERS NOT ONLY TYPICAL GAS MASKS , BUT ALSO BREATHING APPLIANCES ' ' OF ALL KINDS ' ' , ADDING :
' ' A MORE SIMPLE TYPE PROTECTS ONLY THE MOUTH AND THE NOSE ; IT CONSISTS OF A SHEATH HELD IN PLACE BY ONE OR MORE ELASTIC RIBBONS , AND CONTAINS A FILTERING OR ABSORBENT MATERIAL ( ASBESTOS WOOL , SPONGE RUBBER , COTTON WADDING , ETC ., WHICH MAY BE IMPREGNATED OR NOT ) EASILY REPLACED AFTER USE ' ' .
10 THE COMMISSION RELIES ON THE FACT THAT THE LIST OF PRODUCTS NOT COVERED BY TARIFF HEADING 90.18 WAS ADDED TO AS FOLLOWS BY THE CUSTOMS COOPERATION COUNCIL IN OCTOBER 1979 , TO SUPPORT THE CONCLUSION THAT THE MASKS IN QUESTION COME WITHING HEADING 59.03 :
' ' MASKS FOR PROTECTION AGAINST DUST , ODOURS , ETC ., NOT EQUIPPED WITH A REPLACEABLE FILTER , BUT CONSISTING OF SEVERAL LAYERS OF BONDED FIBRE FABRIC , WHETHER OR NOT TREATED WITH ACTIVATED CARBON OR HAVING A CENTRAL LAYER OF SYNTHETIC FIBRES ( HEADING 59.03 ) ' ' .
11 HOWEVER , AS THE COURT STATED IN ITS JUDGMENT OF 15 FEBRUARY 1977 IN JOINED CASES 69 AND 70/76 ( DITTMEYER ( 1977 ) ECR AT P . 238 ), ALTHOUGH THE OPINIONS OF THE COMMITTEE ON COMMON CUSTOMS TARIFF NOMENCLATURE CONSTITUTE AN IMPORTANT MEANS OF ENSURING THE UNIFORM APPLICATION OF THE COMMON CUSTOMS TARIFF BY THE CUSTOMS AUTHORITIES OF THE MEMBER STATES AND AS SUCH MAY BE CONSIDERED AS A VALID AID TO THE INTERPRETATION OF THE TARIFF , NEVERTHELESS SUCH OPINIONS DO NOT HAVE LEGALLY BINDING FORCE SO THAT , WHERE APPROPRIATE , IT IS NECESSARY TO CONSIDER WHETHER THEIR CONTENT IS IN ACCORDANCE WITH THE ACTUAL PROVISIONS OF THE COMMON CUSTOMS TARIFF AND WHETHER THEY ALTER THE MEANING OF SUCH PROVISIONS .
12 THE SAME CONCLUSION MUST