| olm | Microsoft Office Outlook for Mac Database |
| ols | Microsoft Office List Shortcut Data |
| ols | WinOLS OLS Data |
| olt | Orbit Downloader List Data |
| olx | Open Learning XML Data |
| oly | Act! Opportunities Layout |
| oly | AFP Overlay Resource |
| om | STK Owner/Mission File |
| om3 | HALCON Object Model 3D Data |
| omar | SOCSIM Output Marriage File |
| omb | Omnibus Offline Web Storage Data |
| omcs | Office Manager SQL Archive |
| omd | Routing J Server Data |
| omeg | Mathematica for Mac OMEG Data |
| omf | Open Media Framework File |
| omf | Routing J Server Routing Data |
| omfi | Open Media Framework File |
| omlog | CA OM Web Viewer Log |
| omm | OptiMatrix Maker Data |
| omn | Omnipotent Collection Text |
| omr | OMR Reader Template |
| oms | LightShow Pro Optimized Media Sequence |
| oms | Order Maven Data |
| omt | SITH HLA Object Model Template |
| omu | eXtendable Wad Editor OMU Data |
| omx | hyperMILL CAM Temporary Calculation Data |
| omx | OMAX Routed Data File |
| onbatch | ON1 Photo Batch Data |
| ond | Lotus Notes Database |
| one | EdgeCAM Licensing Data |
