M
 MACHINE SHOPS ( 5 )  MACHINE TOOLS ( 19 )  MACHINERY ( 33 )
 MACHINERY PARTS SUPPLIES AND MTC ( 26 )  MAGNETS AND MAGNETIC DEVICES ( 1 )  MARBLE AND GRANITE ( 4 )
 MARINE EQUIPMENT AND SUPPLIES  MARKET RESEARCH AND ANALYSIS  MARRIAGE HALLS ( 1 )
 MATERIAL H AND LING EQUIPMENT ( 4 )  MATRIMONIAL  MATTRESSES AND BEDDING ( 1 )
 MEASURING INSTRUMENTS PRECISION ( 3 )  MEDICAL EQPT AND SUPPLIES ( 6 )  METAL CUTTING MACHINES ( 1 )
 METAL DETECTORS  METAL FINISHING CHEMICALS AND EQUIPMENT ( 1 )  METAL TESTING ( 2 )
 METAL WORKING MACHINERY  METALLIZING  METALLURGIST EQUIPMENT AND SUPPLIES
 METALS AND ALLOYS ( 2 )  METERS ( 1 )  MICA AND MICA PRODUCTS
 MICROFILMING EQUIPMENT  MICROSCOPES  MINERAL PROCESSING EQPTS
 MINERALS  MINING EQUIPMENT AND SUPPLIES  MIRRORS
 MOLASSES  MOTION FILM PROCESSING LAB  MOTION PICTURE FILM
 MOTION PICTURE PRODUCERS AND STUDIOS  MOTOR TRAINING SCHOOLS ( 1 )  MOULDERS
 MUSICAL INSTRUMENTS ( 7 )