| a2x | DragonDictate a2x Data |
| a5r | Macromedia Authorware v5 Runtime |
| a8s | Anim8or Script |
| aaxplugin | Avid Pro Tools Audio eXtension Plugin |
| abi | AbiWord Plug-in File |
| accda | Microsoft Access Add-in |
| aco | Adobe Photoshop Custom Swatch |
| acp | Microsoft Office Assistant Preview |
| acroplugin | Adobe Acrobat Plugin |
| acsauto | Avaya CMS Script |
| act | Microsoft Office Assistant Actor |
| acv | Adobe Photoshop Custom Curve |
| add | Adobe PageMaker Plugin |
| add | Microsoft Dynamics AX Application Developer Documentation Data |
| addon | Zaplots CFS Console Add-on |
| adev | AppleTalk Data Connection File |
| adi | Microsoft Dynamics AX Application Developer Documentation Index |
| ado | Adobe Photoshop Duotone Settings |
| aee | ASUS Data Security Manager Encrypted File |
| aef | Cisco Unity Express Script |
| aex | Adobe After Effects Plug-in |
| agx1 | Adobe FreeHand for Mac Plug-in |
| ahd | Microsoft Dynamics AX Online Help Data |
| ahi | Microsoft Dynamics AX Online Help Index |
| ahq | Creative Audio HQ Plug-in |
| ai65 | Adobe PageMaker 6.5 for Mac Plugin |
| aip | Adobe Illustrator Plugin |
| aix | IBM AIX System File |
| aiz | Aero AIO Plug-in |
| akwf | Oracle ZFS Storage Appliance Workflow |
| almn | Mac OS X Location Manager Module |
| alt | Microsoft Dynamics AX Application Label Temporary File |
| amio | Adobe Audition AMIO Plugin |
| amxx | AMX Mod X Plugin |
| aoi | Microsoft Dynamics AX Application Object Index |