| odif | Open Document Interchange Format Data |
| odl | Microsoft OneDrive Client Log |
| odlgz | Microsoft OneDrive Client Log |
| odlsent | Microsoft OneDrive Client Sent Log |
| odn | Fluke Power Analyze Database |
| odt | Origin Dialog Theme Data |
| odu | Odigo Messenger User Data |
| odv | Ocean Data View Data |
| odx | Microsoft BizTalk Server Orchestration File |
| oe3 | OpenCanvas 3 Event Data |
| oe4 | OpenCanvas 4 Event Data |
| oe5 | OpenCanvas 5 Event Data |
| oeaccount | Windows Mail Account Data |
| oeb | Outlook Express Backup Wizard Data |
| oec | OE-Cake File |
| oef | IBM Optim Export Format Data |
| oes | OpenCanvas 2 Event Data |
| oet | eSignal Order Entry Ticket Data |
| ofa | Kodak OfotoNow Data |
| off | Geomview Binary OFF Data |
| ofl | OtsAV File List |
| ofl_en | OtsAV File List |
| ofm | TopLevel OfficeForms Blank Form |
| ofm | Melco Embroidery Data |
| ofr | Microsoft SMS Offer File |
| ofv | DOpus Saved Favorites |
| ofw | TopLevel OfficeForms Form |
| ogc | Impulse Organica Model Data |
| ogex | Open Game Engine Exchange Data |
| ogg | Origin Graphs Data |
| ogl | Molden OpenGL Model |
| ogm | Origin Matrix Data |
| ogo | Origin Graphic Object |
| ogs | Origin LabTalk Script File |
| ogs | Origons Movie Data |