| aoc | IBM Tivoli Network Manager AOC File |
| aod | Microsoft Dynamics AX Application Object Data |
| aof | Artlantis Object File |
| aom | openEHR Archetype Object Model |
| aop | O&P Industry AOP Data |
| aot | Novell Application Object Template |
| aov | ASReml ANOVA Calculations Data |
| ap11 | Siemens TIA V11 File |
| ap2 | ActivPrimary Resource |
| ap5 | Koyo Screen Creator 5 Transmission File |
| apa | RSView Application Manager Archive |
| apalbum | Apple Aperture Album |
| apb | Alphacam Punch VB Macro |
| apb | LonWorks Binary Neuron Application Image File |
| apdisk | Mac OS X Disk Information File |
| apf | Autodesk Showcase Packet File |
| apf | Adobe Profile Format File |
| apg | PowerADA APG File |
| aph | Ability Album |
| api | Adobe Photoshop Ink Colors Setup |
| apkg | Anki Exported Flashcard Deck |
| aplibrary | Apple Aperture Library |
| apm | Alphacam Punch Param Macro |
| app | Alphacam Punch Post Data |
| appcache | HTML5 Application Cache |
| appl | BoxGrinder Appliance Data |
| apple | Apple AppleSingle Data |
| application | ClickOnce Deployment Manifest |
| apr | Gerber Aperture Data |
| apr_lib | Altium Designer Aperture Library Data |
