| ang | CYANA Torsion Angle File |
| anki | Anki Data |
| anl | Alphacam Nest List |
| anme | Anime Studio Document |
| ann | Windows Help Annotations |
| annot | FreeSurfer Annotation |
| ano | Vaa3D ANO Data |
| anp | Annotis Mail Data |
| ans | HotDocs Answer |
| ansym | Adobe Edge Animate Library |
| ant | Xilinx ISE ANT File |
| ant | Radio Mobile Antenna Definition |
| anw | Anno Wallet Backup File |
| anx | HotDocs Answer |
| any | AnyRail Layout Plan |
| 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 | LonWorks Binary Neuron Application Image File |
| apb | Alphacam Punch VB Macro |
| apdisk | Mac OS X Disk Information File |
