| aop | O&P Industry AOP Data |
| aorder | FotoMagica Data |
| aot | Novell Application Object Template |
| aot | ZENworks snAppShot Application Binary Object Template |
| aov | ASReml ANOVA Calculations Data |
| ap | Entrypoint 90 Application |
| 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 |
| apd | Adobe PageMaker Printer Description |
| apdb | Apple Photos Database |
| apdisk | Mac OS X Disk Information File |
| apertureedit | Apple Aperture Edit Data |
| apf | Adobe Profile Format File |
| apf | ATO Profile Data |
| apf | Autodesk Showcase Packet File |
| apfacename | Apple iPhoto Face Data |
| apfolder | Apple Photos Folder Data |
| apg | PowerADA APG File |
| aph | Ability Photoalbum Album Data |
| api | Adobe Photoshop Ink Colors Setup |
| apin | Adobe InDesign Filter |
| apkg | Anki Exported Flashcard Deck |
| aplibrary | Apple Aperture Library |
| aplmodel | iCal Application Layout Data |
| apm | Alphacam Punch Param Macro |
