| 000 | Data file (GEOWorks) |
| 000-20009 | Used to number old (backup) versions of files (for example, CONFIG.SYS when changed by an installation program); also used to number related data files for multiple users of a small-scale PC application |
| 001-999 | Database index files used by (Superbase) |
| 113 | Backup data file (Iomega Backup) |
| 1ST | Documenting wizard list (Microsoft Visual FoxPro) |
| 3DR | 3DMark Benchmark File |
| 7z | 7-Zip open source file archive format with high compression ratio |
| 8 | Source file (Assembly) (Similar to Microsoft Assembler) |
| netCDF | Network Common Data Form |
