| ojz | Océ Publisher Compressed Job |
| ok | Dot OK MD5 Hash |
| okd | Lenovo OneKey Recovery Data |
| okm | Open Knowledge Management Script |
| okozo | Okozo Desktop Animation Data |
| okp | srDraw Dynamic Image Data |
| okr | PowerRecover One Key Recovery File |
| ol | Altair FEKO Charges Data |
| olb | Cadence OrCAD Binary Library Database |
| olb | Microsoft Office OLE Object Library |
| olb | PSpice Capture Symbols Model |
| olb2 | CanOpener Library |
| ole2 | Microsoft Office OLE2 Stream |
| olecf | OLE 2 Compound File |
| oledata | Microsoft Office Database Connection Data |
| oledata | Microsoft Office List Shortcut Data |
| oledata | Microsoft Office OLE Object Library |
| oledata | Microsoft Office Rendering Data |
| oledata | Microsoft Office Toolbar Button Data |
| olg | OATS Log File |
| olg | Orbit Legend Data |
| olif | Open Lexicon Interchange Format |
| olk | Microsoft Outlook Address Book |
| olk14 | Microsoft Outlook for Mac Message Data |
| olk14arrange | Microsoft Office Outlook for Mac Arrange Data |
| olk14category | Microsoft Office Outlook for Mac Category Data |
| olk14contact | Microsoft Office Outlook for Mac Contacts Data |
| olk14event | Microsoft Office Outlook for Mac Events Data |
| olk14exmoves | Microsoft Office Outlook for Mac Data |
| olk14folder | Microsoft Office Outlook for Mac Folder Data |
| olk14group | Microsoft Office Outlook for Mac Group Data |
| olk14message | Microsoft Office Outlook for Mac Message Pointer |
| olk14msgsource | Microsoft Office Outlook for Mac Message Data |
| olk14note | Microsoft Office Outlook for Mac Note |
| olk14recent | Microsoft Office Outlook for Mac Recent Address Data |
