| Abbreviation | Definition |
|---|---|
| OFF | Vector graphics (Object File Format) |
| OFM | PostScript font description file |
| OFN | Document (MS Office) |
| OFT | Microsoft Outlook Item template |
| OGF | OnkoS Graphic File |
| OGF | Outrage Graphics File |
| OHS | Outbound History (Bink/+) |
| OID | Object Interaction Diagram ( Prosa/ OM) |
| OKT | Oktalyzer 8-channel Music format |
| OLB | Object library (VAX) |
| OLB | OLE object library |
| OLD | Backup file |
| OLE | OLE object |
| OLI | Olivetti Text file |
| OLK | Address book (MS Outlook) |
| OMD | Prosa/OM Class model file |
| OME | Weather Observation Definition Format |
| OMF | OMF Interchange file |
| OOBE | Out Of Buggy Experience |
| OOM | Shroom Swap File |