OPINION ON THE: PROPOSAL FOR A COUNCIL DIRECTIVE AMENDING DIRECTIVE 71/316/EEC ON THE APPROXIMATION OF THE LAWS OF THE MEMBER STATES RELATING TO COMMON PROVISIONS FOR BOTH MEASURING INSTRUMENTS AND METHODS OF METROLOGICAL CONTROL; PROPOSAL FOR A COUNCIL DIRECTIVE AMENDING DIRECTIVE 76/764/EEC ON THE APPROXIMATION OF THE LAWS OF THE MEMBER STATES ON CLINICAL MERCURY-IN-GLASS, MAXIMUM-READING THERMOMETERS; PROPOSAL FOR A COUNCIL DIRECTIVE ON THE APPROXIMATION OF THE LAWS OF THE MEMBER STATES RELATING TO TYRE PRESSURE GAUGES FOR MOTOR VEHICLES; PROPOSAL FOR A COUNCIL DIRECTIVE ON THE APPROXIMATION OF THE LAWS OF THE MEMBER STATES RELATING TO INSTRUMENTS DESIGNED TO DETERMINE THE CONTENT BY VOLUME OF CARBON MONOXIDE IN THE EXHAUST GASES OF MOTOR VEHICLES WITH SPARK IGNITION