| nnn | Filmetrics F20 Material Data |
| nnp | ANNI Neural Network Portfolio |
| nnr | NeuralWare NeuralWorks Data |
| nns | NobleNet Sealer File |
| nnt | Eudora Addressbook Database |
| nntp | NewsWatcher NNTP Data |
| nnvs | NextNine VNC Player Session Data |
| nnw | NobleNet Web Data |
| nob | Chart Navigator Pro Navigation Objects Data |
| nod | MSC Patran Nodal Results |
| nodes | PowerFolder Nodes Data |
| nog | BLAST NOG Data |
| nom | PC-DMIS NOM File |
| nop | Nikon Optional Picture Control |
| nopd | Navicat for Oracle Data Synchronization Profile Data |
| nope | Navicat for Oracle Exported Table |
| nopem | Navicat for Oracle Export Materialized View Profile |
| nopeq | Navicat for Oracle Export Query Result Profile Data |
| nopev | Navicat for Oracle Export View Result Profile Data |
| nopi | Navicat for Oracle Import Wizard Profile Data |
| nopj | Navicat for Oracle Batch Job |
| nops | Navicat for Oracle Structure Synchronization Data |
| nopt | Navicat for Oracle Data Transfer Profile Data |
| not | Adobe InCopy User Dictionary |
| not | MakeMusic Finale Note File |
| not | Zemax Element Drawing Note |
| notx | E-Sword v9 Study Note |
| notz | FiiNote Exported Note |
| nou | Numerical Electromagnetics Code Output |
| nov | Native Instruments Battery Data |
| novs | Novell NetWare Control Center Data |
| nox | Wave IRIS NOx Data |
| nozskin | WinDS PRO NOZSkin Data |
| np2 | Nikon Picture Control v2 Data |
| np3 | NP3 Compressed Nucleotide Database |