| 85950 | Names and addresses, compiling and selling lists of | |
| 85122 | Nannies, supplying of, for employment by others | |
| 96310 | Narrators, services of | |
| 91210 | National boundaries, distribution of cultural information beyond | |
| 91124 | National festivities, support services for | |
| 96422 | National parks, conservation of | |
| 96422 | National parks, maintenance of | |
| 96422 | National parks, supervision of | |
| 91132 | Natural gas, administrative services related to | |
| 65122 | Natural gas, coastal water transportation of, in special tankers | |
| 65222 | Natural gas, inland water transportation of, in special tankers | |
| 86210 | Natural gas, liquefaction of, for transportation | |
| 86210 | Natural gas, regasification of, for transportation | |
| 65122 | Natural gas, transoceanic water transportation of, in special tankers | |
| 64122 | Natural gas, transportation of, by railway in special tank cars | |
| 64232 | Natural gas, transportation of, by road in special tank trucks | |
| 64310 | Natural gas, transportation of, via pipeline | |
| 81190 | Natural sciences, other, research and experimental development concerning | |
| 91114 | Natural sciences, the, administrative services related to research into | |
| 96422 | Nature reserve services including wildlife preservation services | |
| 96422 | Nature reserves, conservation of | |
| 96422 | Nature reserves, maintenance of | |
| 96422 | Nature reserves, services of | |
| 96422 | Nature reserves, supervision of | |
| 87154 | Navigation instruments, maintenance and repair of | |
| 67300 | Navigation, buoys and similar aids to, services of | |
| 67300 | Navigation, channel markers and similar aids to, services of | |
| 67300 | Navigation, lighthouses and similar aids to, services of | |
| 67300 | Navigation, lightships and similar aids to, services of | |
| 67300 | Navigational aid locating services, radio | |
| 67300 | Navigational aid services | |
| 83820 | Negatives, developing of | |
| 83820 | Negatives, enlargement of | |
| 83820 | Negatives, photographic, duplication of | |
| 83820 | Negatives, photographic, reprinting of | |
| 71620 | Negotiating settlements of insurance claims | |
| 62332 | Net curtains, mail order retail trade services of | |
| 62132 | Net curtains, non-specialized store retail trade services of | |
| 62432 | Net curtains, other non-store retail trade services of | |
| 62532 | Net curtains, retail trade services of, on a fee or contract basis | |