| .A-0 | Unknown Developer | File vari | Unknown File Type | Unknown Software | Unknown Developer |
| .A021 | Unknown Developer | File vari | Unknown File Type | Unknown Software | Unknown Developer |
| .A1J | Unknown Developer | File vari | Unknown File Type | Unknown Software | Unknown Developer |
| .A2 | Apple | File di dati | Golden Orchard Apple II CD Rom File | Unknown Software | Unknown Developer |
| .A3 | Apple | File di dati | Golden Orchard Apple II CD Rom File | Unknown Software | Unknown Developer |
| .A349 | Unknown Developer | File vari | Unknown File Type | Unknown Software | Unknown Developer |
| .A4J | Unknown Developer | File vari | Unknown File Type | Unknown Software | Unknown Developer |
| .A68 | Digital Equipment Corporation | File sviluppatore | PDP-10 Algol-68 Compiler Source | Unknown Software | Unknown Developer |
| .A8 | Cubicomp | File con immagini raster | Cubicomp PictureMaker 3D Animation Data | Unknown Software | Unknown Developer |
| .AA48 | Unknown Developer | File vari | Unknown File Type | Unknown Software | Unknown Developer |
| .ABB | Unknown Developer | File di dati | AlphaBB Data | Unknown Software | Unknown Developer |
| .AC7 | National Instruments | File di dati | SPICE AC/Frequency Domain Output File | Unknown Software | Unknown Developer |
| .ACT | Bell Labs | File audio | ADPCM Compressed Audio File | Unknown Software | Unknown Developer |
| .ACTBIN | Unknown Developer | File vari | Unknown File Type | Unknown Software | Unknown Developer |
| .ACUTC | Unknown Developer | File vari | Unknown File Type | Unknown Software | Unknown Developer |
| .ADRESSES | Apple | File di dati | Golden Orchard Apple II CD Rom File | Unknown Software | Unknown Developer |
| .AEG | Unknown Developer | File vari | Netmino File | Netmino | Unknown Developer |
| .AFAE | Unknown Developer | File vari | Unknown File Type | Unknown Software | Unknown Developer |
| .AFX FILE EXTENSION | Unknown Developer | File vari | Unknown File Type | Unknown Software | Unknown Developer |
| .AHF | Anadigm | File di dati | AnadigmDesigner ASCII Code | Unknown Software | Unknown Developer |
| .AHQ | Unknown Developer | File con plugin | AudioHQ Plug-in Module | Unknown Software | Unknown Developer |
| .AHR0CDOVL2 | Unknown Developer | File vari | Unknown File Type | Unknown Software | Unknown Developer |
| .AIN | Valve | File di giochi | Source Engine Compiled AI Nodegraph File | Multi Unpacker | Unknown Developer |
| .AINSO | Unknown Developer | File di dati | CRYSTALS Chemical Crystallogaphy File | CRYSTALS | Unknown Developer |
| .AJ0 | Unknown Developer | File vari | Uncommon File Extension | Unknown Software | Unknown Developer |
| .AJO | Unknown Developer | File vari | Uncommon File Extension | Unknown Software | Unknown Developer |
| .AK | Unknown Developer | File compressi | Audio Utility Tuningwrench Compressed File | Unknown Software | Unknown Developer |
| .ALBM | Hewlett-Packard | File con immagini raster | HP Photo Printing Software Album File | Unknown Software | Unknown Developer |
| .ALDRIN | Apple | File di dati | Golden Orchard Apple II CD Rom File | Unknown Software | Unknown Developer |
| .APG | Unknown Developer | File grafici | Ivana Animated GIF File | Unknown Software | Unknown Developer |
| .APN | Alpine Electronics | File 3D | Alpine Wallpaper | Unknown Software | Unknown Developer |
| .APPS | Apple | File di dati | Golden Orchard Apple II CD Rom File | Unknown Software | Unknown Developer |
| .ARCH | Unknown Developer | File di dati | Illum Source Dotfiles File | Unknown Software | Unknown Developer |
| .ARMOURFONT | Apple | File di dati | Golden Orchard Apple II CD Rom File | Unknown Software | Unknown Developer |
| .ASXP | Unknown Developer | File vari | Unknown File Type | Unknown Software | Unknown Developer |
| .AT | Unknown Developer | File vari | Rescue Disk File | Unknown Software | Unknown Developer |
| .ATG | Unknown Developer | File vari | Netmino File | Netmino | Unknown Developer |
| .ATOS | Unknown Developer | File vari | Unknown File Type | Unknown Software | Unknown Developer |
| .ATW | Unknown Developer | File di dati | Attityd Survey Program Data | Unknown Software | Unknown Developer |
| .AUDIO | Apple | File di dati | Golden Orchard Apple II CD Rom File | Unknown Software | Unknown Developer |
| .AVH | Pioneer DJ Corporation | File di dati | Pioneer AVH Firmware Update | OXE CCTV DVR Recorder | Unknown Developer |
| .AW_ | Unknown Developer | File compressi | Midiprg Quartz Sets Compressed File | Unknown Software | Unknown Developer |
| .AY | Richard Bannister | File audio | AY Chiptune File | Micro Speccy | Unknown Developer |
| .AYA | Unknown Developer | File vari | Uncommon File Extension | Unknown Software | Unknown Developer |
| .AYE | Unknown Developer | File vari | Unknown File Type | Unknown Software | Unknown Developer |
| .AZA | Unknown Developer | File compressi | QazaR Archive Compressed File | QazaR | Unknown Developer |
| .AZX | Unknown Developer | File audio | ZX Audio File Format | Unknown Software | Unknown Developer |
| .A_T | Unknown Developer | File di dati | Atrain File | Unknown Software | Unknown Developer |
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