File Extensions beginning with the letter 'O'

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Extension currently sorted on Extension Description click to sort by Description Format MIME Type
O Atari or UNIX object file; see OBJ
o object file
O01 Typhoon voice file
OAZ Fax Document; OAZ Fax
OB$ Microsoft compressed OBJ; decompress with UNPACK.EXE
OBD Microsoft Office binder template
OBD Microsoft Office Binder
OBD Microsoft Office Binder
OBD Office Binder (vers 7.0)
OBJ Wavefront Object. Details
obj object file
OBR Object Browser State file (Borland C++)
OBT Office Binder Template (vers. 7.0)
OBT Microsoft Office Binder Template
OBV ObjectScript
OBZ Office Binder Wizard (vers 7.0)
OBZ Microsoft Office Binder Wizard
OBZ Microsoft Office Binder Wizard
OCA OLE Custom Control Library Information
oca MS control typelib cache file
OCF Object Craft
OCR Generic
OCX OLE Custom Control (not necessarily 32-bits, not necessarily Basic)
ocx OLE control extension
OCX Microsoft Object Linking and Embedding custom control
ODA (1) Used with OCX
ODA (2) Document; Open Document Architecture Consortium; ODF
ODB Document; Microsoft Office 97 Binder; see ODT
ODF Document; Open Document Interchange Format; ODA
ODIF Open Document Interchange Format
ODL Object Description Language
ODL Object Definition Language (Object Library Source for OLE applications)
ODS Microsoft Outlook Express mailbox file (?)
ODS NCompass Labs (Internet script?)
ODT Document; Microsoft Office 97 Binder; see ODB
ODT OOMF Data Table. Data from the Object Oriented Micromagnetic Framework. Details
ODT Open Document Text. A standard file format for word processing documents.
OFD ObjectView Form Definition
OFF Object File Format. Vector image. Details
OFN Microsoft Office FileNew file
OFN Microsoft Office File New (Other Office Documents)
OFT Microsoft Outlook template
OGG A type of audio/video file.
OGM OGG Media Stream. Audio/Video. command line tools.
OGX Microsoft C++ Component Gallery exported classes and resources
OKT Oktalyzer music module (MOD) file
OKT Sound; Oktalyzer Module
OLB (2) AUTOGEN file
OLB (1) Microsoft Project Object Library
OLB OLE Object Library
OLB (3) VAX Object Library
OLD Backup
OLE Object Linking and Embedding Object (generic name)
OLE OLE object
OLI Document; Olivetti
OLIF Open Lexicon Interchange Format, is a user-friendly vehicle for exchanging terminological and lexical data. More Info.
OLK Microsoft Mail mailbag lock; see MAI
OLN Outline (Microsoft Visual C++ Outline examples use this extension)
OLT Outline (Microsoft Visual C++ Outline examples use this extension)
OOGL Picture; Web Object Oriented Graphics Library
OOGL Object Oriented Graphics Library
OPC Microsoft Office 97 upgrade wizard clean-up (like a setup script)
OPF Open eBook Package File. More Info.
OPL Organiser Programming Language source file - Psion/Symbian
OPL PSION Organizer; see AGN
OPO OPL output executable file
OPT Microsoft Developer Studio file
OPT (2) Microsoft Developer Studio workspace options
OPT (1) Delphi Project Options (text, current project settings)
OPW Org Plus organizational chart
OPW Microsoft Organization Chard
OPX OPL extension DLL
OPX Microsoft Organization Chard
OPX (1) Chart; Banner Blue Org Chart; see MPO
OPX (2) Microsoft Office Organization Chart (also by Banner Blue)
OR2 Lotus Organiser 2 file
OR2 Lotus Organizer 2
OR3 Lotus Organiser 97 file
OR3 Lotus Organizer 97
OR4 Lotus Organizer 4
ORA Oracle 7 configuration
ORA Oracle Database
ORC Oracle 7 script
ORF Olympus Raw Format. Raster image from an Olympus digital camera. [RAW]
ORG Lotus Organiser file
ORG Lotus Organizer calendar
OS/2 Bitmap
OS/2 Warp Bitmap
os2 OS/2 bitmap
osd Open Software Description. An XML format with the details of a software package. Details.
OSS Microsoft Office Search file
OSS Microsoft Office Saved Search
OST Microsoft Outlook off-line folder
OST Microsoft Exchange/Outlook Offline file
OTH .OtherFolder, Microsoft Power Toys Explorer tool
OTL Super NoteTab template file (Fookes)
OTX Document; Olivetti Olitext
OUT SmartOutline outline file.
ovl overlay files
OVR Program Overlay
ow4 OfficeWriter
OYZ Lotus Approach alternate dBASE index; created if ADX file is used by another application
OZM Sharp Organizer Memo Bank
OZP Sharp Organizer Telephone Bank