| 1 | NRP | Aeronord-Grup | Callsign: Aeronord, | MD | AVCODES |
| 2 | NRP | Aeronord-Grup | | | ICAO1 |
| 3 | NRPI | NORMAN, R & P INC | | | SCAC3 |
| 4 | NRPK | NORPAK CORP | | | SCAC4 |
| 5 | NRPP | NORRICK PETROLEUM PRODUCTS INC | | | SCAC4 |
| 6 | NRPX | Northrop Corp. | added 4/1990; 1/1994; eliminated 7/1994; 7/2000-7/2005 (not listed) | | NAKINA |
| 7 | NRPX | National Rosin Oil & Size Co. | 8/1920-7/1935 | | NAKINA |
| 8 | NRPX | Northrop Corp. | added 4/90; 1/94; eliminated 7/94; 7/2000 | | NRHS |
| 9 | NRPX | *NATIONAL ROSIN OIL & SIZE CO. | | | PWRC |
| 10 | NRPX | +NORTHROP CORPORATION | | | PWRC |
| 11 | NRPX | Northrop Corporation | | | RSRV |
