| otvdatafile | onlineTV Data |
| otvlangfile | onlineTV Language Data |
| otx | theWord Encrypted Old Testament Text Module |
| otz | OpenLP Theme File |
| oub | Oubliette Data |
| oud | Adlib Express User Defined Dictionary |
| ouf | Otravi Unit Frames Data |
| out | Altair FEKO POSTFEKO ASCII Output Data |
| BibExcel OUT Data |
| Catapult DCT2000 Trace Data |
| FAST Output Data |
| Fire Dynamics Simulator Output Data |
| Movie.BYU Output Data |
| MyInfo Document Outline Data |
| Nastran Tabular Output |
| NovaBACKUP Backup Data |
| RMCProfile Results Data |
| out1 | UltraEdit Outline Data |
| outb | FAST Binary Output Data |
| outjob | Altium Designer OutputJob Data |
| outline | FontTwister Letter Outline Data |
| ouv | Sphinx Open Ended Responses Data |
| oux | BibExcel OUX Data |
| PCCharge Transaction Response XML File |
| ov | OpenInsight Overflow Data |
| ov1 | MS-DOS Overlay Data |
| ov2 | MS-DOS Overlay Data |
| TomTom POI Database |
| ov3 | MS-DOS Overlay Data |
| ov4 | MS-DOS Overlay Data |
| ov5 | MS-DOS Overlay Data |
| ova | Web Studio Project Page |
| ovb | OnkoS Vocabulary Backup Data |
| ovd | OverDisk Data |
| overlay | Streamlabs OBS Overlay Data |
| ovf | Open Virtualization Format Data |
| ovi | PC-9801 FM System Data |
| ovisuite | Nokia Ovi Suite Data |
| ovl | E-Sword v8 Overlay Data |
| ovlx | E-Sword v9 Overlay Data |
| ovm | BHV Tonstudio Data |
| ovml | Ovidentia Markup Language Document |
| ovo | Euronda Autoclave Cycle Data |
| ovolog | ooVoo Log File |
| ovs | ARTA Overlay Data |
| Orbit Vector Symbol Data |
| Ovation 1 Style Sheet |
| ovt | Orbit Vector File Tiled |
| ovw | Cool Edit Pro Overview Data |
| Cubase WAVE File Overview |
| Logic Pro Overview Data |
| owc | OutWit Hub OutWit Catch Database |
| WAsP Observed Wind Climate |
| owf | OSRAM Waveform File |
| owg | OutWit Hub Gear Database |
| owm | OutWit Hub XML Mashup |
| owpml | Hangul Word Processor 2018 Document |
| owt | OneWorldTree Data |
| owx | OutWit Hub Script |
| oxb | OlapX Report Portfolio Data |
| oxc | OlapX Cube Definition |
| oxd | PS3 Proxy Server Data |
| oxe | Pulsar Z.matrix Data |
| oxf | IBM Rational Rhapsody Data |
| Orbit XML Vector Data |
| Origin X-Function File |
| oxl | LITESTAR 4D Data File |
| oxml | OXML 2.0 Data |
| oxp | OmniRush eXtended Package |
| oxv | OlapX Local View Data |
| oxy | Matplotlib OXY Data |
| oyb | Organize Your Beanie Babies Data |
| oyx | Lotus Approach Alternate Database Index |
| oyz | Lotus Approach Alternate Database Index |
| oz | Opera Job Management Compressed File |
| ozd | OZ Report Data |
| ozm | Sharp Wizard Memo Bank |
| ozp | Orgadata LogiKal OZP Data |
| Sharp Wizard Phone Bank Data |
| p0 | WOW! Diagnostic P0 Data |
