| .OR3 | IBM | Arquivos de dados | IBM Lotus Organizer 97 File | IBM Lotus Organizer | IBM |
| .OR4 | IBM | Arquivos de dados | IBM Lotus Organizer 97 GS File | IBM Lotus Forms Viewer | IBM |
| .OR5 | IBM | Arquivos de dados | Lotus Organizer 5 File | IBM Lotus Organizer | IBM |
| .OR6 | IBM | Arquivos de dados | Lotus Organizer Data | IBM Lotus Organizer | IBM |
| .ORC | Voyetra Turtle Beach | Arquivos de dados | Voyetra Digital Orchestrator File | Digital Orchestrator | Voyetra Turtle Beach |
| .ORD | OMAX Corporation | Arquivos de dados | OMAX Routed Data | Unknown Software | Unknown Developer |
| .ORG | IBM | Arquivos de dados | Lotus Organizer File | IBM Lotus Organizer | IBM |
| .ORIGINAL | NetObjects | Arquivos de dados | Netobjects Fusion Components Bbscomp Message Data | NetObjects Fusion | NetObjects |
| .ORM | Ormetis S.A.S. | Arquivos de dados | Ormetis Workbench Data | Ormetis | Ormetis S.A.S. |
| .ORP | PV & Associates | Arquivos de dados | WinSLAM File | WinSLAMM | PV & Associates |
| .OS | Open Source | Arquivos de dados | ObjectScript Source File | ObjectDevel | Open Source |
| .OSA | Symantec Corporation | Arquivos de dados | W32/Sober-AD File | AVG Antivirus | AVG Technologies |
| .OSD | Microsoft Corporation | Arquivos de dados | Open Software Description Data | Microsoft Application Virtualization | Microsoft Corporation |
| .OSI | Jamie Wilkinson | Arquivos de dados | Osiris Database | Osiris | Jamie Wilkinson |
| .OSL | Ockam Instruments | Arquivos de dados | OckamSoft Log File | OckamSoft | Ockam Instruments |
| .OSMALLER | Unknown Developer | Arquivos de dados | Unknown Apple II File. (found On Golden Orchard Apple II CD Rom) | Atom | GitHub, Inc. |
| .OSZ | Ppy Pty Ltd | Arquivos de dados | Osu! Beatmap File | osu! | Ppy Pty Ltd |
| .OT | Open Source | Arquivos de dados | TheWord Old Testament Text Module | theWord | Costas stergiou |
| .OTL | Fookes Software | Arquivos de dados | NoteTab Outline File | NoteTab | Fookes Software |
| .OTN | Nuance | Arquivos de dados | OmniPage Training File | OmniPage | Nuance |
| .OTP | Oracle Corporation | Arquivos de dados | OpenDocument Presentation | Apache OpenOffice | Apache Software Foundation |
| .OTX | Open Source | Arquivos de dados | TheWord Encrypted Old Testament Text Module | theWord | Costas stergiou |
| .OUT | Open Source | Arquivos de dados | Compiled Executable File | Linux | Open Source |
| .OUV | Le Sphinx | Arquivos de dados | Sphinx Open Ended Responses Data | Sphinx | Le Sphinx |
| .OV | Revelation Software | Arquivos de dados | OpenInsight Database Overflow Data | OpenInsight | Revelation Software |
| .OVA | VMware | Arquivos de dados | Open Virtual Appliance | VMware Workstation | VMware |
| .OVD | Elias Fotinis | Arquivos de dados | OverDisk Database | OverDisk | Elias Fotinis |
| .OVF | VMware | Arquivos de dados | Open Virtualization File | VMware Workstation | VMware |
| .OVLX | Rick Meyers | Arquivos de dados | E-Sword Overlay Data | e-Sword | Rick Meyers |
| .OVX | Psion PLC | Arquivos de dados | Object-based Visual Application Language File | Psion OVAL | Psion PLC |
| .OWC | OutWit Technologies | Arquivos de dados | OutWit Catch Database | Mozilla Firefox | Mozilla |
| .OWF | OSRAM GmbH | Arquivos de dados | OSRAM Waveform File | Unknown Software | Unknown Developer |
| .OZD | Symantec Corporation | Arquivos de dados | Win32.TrojanDownloader.Agent.OZD Trojan | Avira Antivirus Pro 2016 | Avira Operations GmbH & Co. KG. |
| .P | Python Software Foundation | Arquivos de dados | Python Pickle File | Python pickle | Python Software Foundation |
| .P0 | Würth Online World GmbH | Arquivos de dados | WOW! Data | WOW! | Würth Online World GmbH |
| .P06 | Bentley Systems | Arquivos de dados | MicroStation Modification Project Resource File | MicroStation | Bentley Systems |
| .P07 | Peter B. Clements | Arquivos de dados | PAR Recovery Volume | QuickPar | Open Source |
| .P1D | The Danfoss Group | Arquivos de dados | PLUS+1 Data | Plus+1 | The Danfoss Group |
| .P2B | Open Source | Arquivos de dados | PeerGuardian 2 IP Blocking List | PeerGuardian 2 | Open Source |
| .P2C | IBM | Arquivos de dados | IBM Voice Type Languages Newuser File | IBM Voice Type | IBM |
| .P3 | Oracle Corporation | Arquivos de dados | Primavera P3 Project File | Primavera | Oracle Corporation |
| .P38 | Apple | Arquivos de dados | Golden Orchard Apple II CD Rom File | Apple OS X | Apple |
| .P3E | Adobe Systems Incorporated | Arquivos de dados | Photoshop Repousse Settings File | Adobe Photoshop CC | Adobe Systems Incorporated |
| .P3I | Tech4Learning | Arquivos de dados | Pixie File | Pixia | Isao Maruoka |
| .P3L | Adobe Systems Incorporated | Arquivos de dados | Adobe Photoshop Light Preset File | Adobe Photoshop | Adobe Systems Incorporated |
| .P5P | Oracle Corporation | Arquivos de dados | Oracle Solaris Image Packaging System | Solaris | Oracle Corporation |
| .P7X | Microsoft Corporation | Arquivos de dados | Packed Digital Signature File | Microsoft Visual Studio | Microsoft Corporation |
| .P83 | GAEB | Arquivos de dados | GAEB DA 2000 Data | GAEB data exchange XML | GAEB |
| .PA2 | Dr. Hsin H. Huang | Arquivos de dados | STABCAL Data File | STABCAL | Dr. Hsin H. Huang |
| .PAB | Microsoft Corporation | Arquivos de dados | Personal Address Book | Microsoft Outlook Express | Microsoft Corporation |
| .PACK | neOceane | Arquivos de dados | CustoPack Tools Theme Pack | CustoPack Tools | neOceane |
| .PAD | Swiftpage, Inc. | Arquivos de dados | ACT! Database Pointer File | Act! | Swiftpage, Inc. |
| .PAF | FamilySearch | Arquivos de dados | Personal Ancestral File | Personal Ancestral File | FamilySearch |
| .PAG | Microsoft Corporation | Arquivos de dados | Visual Basic Property PAGe File | Microsoft Visual Basic | Microsoft Corporation |
| .PAI | Magix Software GmbH | Arquivos de dados | MAGIX Photo Clinic File | Photo Clinic | Magix Software GmbH |
| .PAM | Open Source | Arquivos de dados | Portable Arbitrary Map | Adobe Photoshop | Adobe Systems Incorporated |
| .PAR | Siemens PLM Software | Arquivos de dados | Solid Edge Part File | Adobe Acrobat DC | Adobe Systems Incorporated |
| .PARAM | Open Source | Arquivos de dados | CASTEP Parameters Data | CASTEP | Open Source |
| .PARSER | Apple | Arquivos de dados | Golden Orchard Apple II CD Rom File | Apple OS X | Apple |
| .PART1 | NetObjects | Arquivos de dados | NetObjects Fusion System Data | NetObjects Fusion | NetObjects |
| .PART2 | NetObjects | Arquivos de dados | NetObjects Fusion System Data | NetObjects Fusion | NetObjects |
| .PASCAL | Apple | Arquivos de dados | Golden Orchard Apple II CD Rom File | Apple OS X | Apple |
| .PASS | Apple | Arquivos de dados | Xcode Wallet Data | Apple Xcode | Apple |
| .PAT | Autodesk, Inc. | Arquivos de dados | AutoCAD Hatch Pattern File | Autodesk AutoCAD | Autodesk, Inc. |
| .PATCHER | Apple | Arquivos de dados | Golden Orchard Apple II CD Rom File | Apple OS X | Apple |
| .PATH | Apple | Arquivos de dados | Golden Orchard Apple II CD Rom File | Apple OS X | Apple |
| .PAUSE | Apple | Arquivos de dados | Golden Orchard Apple II CD Rom File | Apple OS X | Apple |
| .PAV | Peavey Commercial Audio | Arquivos de dados | MediaMatrix Peavey Architectural View Data | MediaMatrix | Peavey Commercial Audio |
| .PAW | SecurelyShare | Arquivos de dados | PawaaFILE File Format | SecurelyShare | SecurelyShare |
| .PAY | Priority Data Sytems | Arquivos de dados | PriorityRate File | PriorityRate | Priority Data Sytems |
| .PAYROLL | Apple | Arquivos de dados | Golden Orchard Apple II CD Rom File | Apple OS X | Apple |
| .PB | Fantaisie Software | Arquivos de dados | PureBasic Source File | PureBasic | Fantaisie Software |
| .PB1 | Broderbund | Arquivos de dados | Broderbund 3D Home Architect Data | 3D Home Architect | Broderbund |
| .PBD | EaseUS | Arquivos de dados | EaseUS Todo Backup Backup File | EaseUS Todo Backup | EaseUS |
| .PBE | Crownhill Associates Limited | Arquivos de dados | Proton Plus Compiler Data | Proton Plus Compiler | Crownhill Associates Limited |
| .PBK | Microsoft Corporation | Arquivos de dados | Dial-Up Phone Book File | Microsoft Windows | Microsoft Corporation |
| .PBR | Sybase, Inc | Arquivos de dados | PowerBuilder Resource File | PowerBuilder | SAP |
| .PBU | PowerBASIC, Inc. | Arquivos de dados | PowerBASIC DOS Compiled Unit | PowerBASIC | PowerBASIC, Inc. |
| .PC | Personal Composer | Arquivos de dados | Personal Composer File | Personal Composer | Personal Composer |
| .PC5 | Rockwell Automation Inc. | Arquivos de dados | RSLogix 5 Internal Data | RSLogix 5 | Rockwell Automation Inc. |
| .PCAP | The Wireshark Team | Arquivos de dados | Packet Capture Data | Wireshark | The Wireshark Team |
| .PCB | Autodesk, Inc. | Arquivos de dados | Printed Circuit Board Design File | CadSoft EAGLE | Autodesk, Inc. |
| .PCBDOC | Altium | Arquivos de dados | Printed Circuit Board Description | Altium Designer | Altium |
| .PCC | Electronic Arts | Arquivos de dados | Mass Effect Package | Mass Effect 3 | BioWare |
| .PCD | PokéCheats | Arquivos de dados | Pokémon Wonder Card File | Pokesav | PokéCheats |
| .PCE | Open Source | Arquivos de dados | TurboGrafx-16 ROM | Magic Engine | Open Source |
| .PCH | MSC Software | Arquivos de dados | Nastran Punch Output File | MSC Nastran | MSC Software |
| .PCK | Microsoft Corporation | Arquivos de dados | System Center Configuration Manager Package File | Microsoft system center configuration manager | Microsoft Corporation |
| .PCP | Microsoft Corporation | Arquivos de dados | Windows Installer Patch Creation Properties File | Microsoft Windows SDK | Microsoft Corporation |
| .PCR | Futuremark Corporation | Arquivos de dados | PCMark Vantage Benchmark File | PCMark | Futuremark Corporation |
| .PCT | Apple | Arquivos de dados | Macintosh PICT Format | Adobe Illustrator CC | Adobe Systems Incorporated |
| .PD | SAI | Arquivos de dados | FlexiSIGN 5 Plotter Document | FlexiSIGN | SAI |
| .PD3 | Autodesk, Inc. | Arquivos de dados | 3D Studio Max Data | Autodesk 3ds Max | Autodesk, Inc. |
| .PD4 | Jan van Wijk | Arquivos de dados | DFSee Partition Table And Boot Sector Backup | DFSee | Jan van Wijk |
| .PD5 | Microsoft Corporation | Arquivos de dados | Windows Live Photo Gallery Information File | Windows Photo Gallery | Microsoft Corporation |
| .PDA | Molecular Devices | Arquivos de dados | SoftMax Pro Microplate Data Analysis File | SoftMax Pro | Molecular Devices |
| .PDAS | hfrmobile | Arquivos de dados | PDAStore Data Store File | PDAStore | hfrmobile |
| .PDATA | Physiome Project | Arquivos de dados | JSim Pretty Data Format | JSim | Physiome Project |
| .PDB | Various Developers | Arquivos de dados | Program Database | Microsoft Visual Studio | Microsoft Corporation |
| .PDD | Adobe Systems Incorporated | Arquivos de dados | Adobe PhotoDeluxe Image | Adobe Illustrator CC | Adobe Systems Incorporated |
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