| .9B | Unknown Developer | Uncommon Files | Unknown Apple II Data File | Unknown Software | Unknown Developer |
| .9DEE5 | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .9T | Apple | Ficheiros de Dados | Golden Orchard Apple II CD Rom File | Unknown Software | Unknown Developer |
| .A-0 | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .A021 | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .A1J | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .A2 | Apple | Ficheiros de Dados | Golden Orchard Apple II CD Rom File | Unknown Software | Unknown Developer |
| .A3 | Apple | Ficheiros de Dados | Golden Orchard Apple II CD Rom File | Unknown Software | Unknown Developer |
| .A349 | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .A4J | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .A68 | Digital Equipment Corporation | Ficheiros de Desenvolvedor | PDP-10 Algol-68 Compiler Source | Unknown Software | Unknown Developer |
| .A8 | Cubicomp | Ficheiros de Imagem Raster | Cubicomp PictureMaker 3D Animation Data | Unknown Software | Unknown Developer |
| .AA48 | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .ABB | Unknown Developer | Ficheiros de Dados | AlphaBB Data | Unknown Software | Unknown Developer |
| .AC7 | National Instruments | Ficheiros de Dados | SPICE AC/Frequency Domain Output File | Unknown Software | Unknown Developer |
| .ACT | Bell Labs | Ficheiros de Áudio | ADPCM Compressed Audio File | Unknown Software | Unknown Developer |
| .ACTBIN | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .ACUTC | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .ADRESSES | Apple | Ficheiros de Dados | Golden Orchard Apple II CD Rom File | Unknown Software | Unknown Developer |
| .AFAE | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .AFX FILE EXTENSION | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .AHF | Anadigm | Ficheiros de Dados | AnadigmDesigner ASCII Code | Unknown Software | Unknown Developer |
| .AHQ | Unknown Developer | Ficheiros Plugin | AudioHQ Plug-in Module | Unknown Software | Unknown Developer |
| .AHR0CDOVL2 | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .AJ0 | Unknown Developer | Uncommon Files | Uncommon File Extension | Unknown Software | Unknown Developer |
| .AJO | Unknown Developer | Uncommon Files | Uncommon File Extension | Unknown Software | Unknown Developer |
| .AK | Unknown Developer | Ficheiros Compactados | Audio Utility Tuningwrench Compressed File | Unknown Software | Unknown Developer |
| .ALBM | Hewlett-Packard | Ficheiros de Imagem Raster | HP Photo Printing Software Album File | Unknown Software | Unknown Developer |
| .ALDRIN | Apple | Ficheiros de Dados | Golden Orchard Apple II CD Rom File | Unknown Software | Unknown Developer |
| .APG | Unknown Developer | Ficheiros Gráficos | Ivana Animated GIF File | Unknown Software | Unknown Developer |
| .APN | Alpine Electronics | Ficheiros de Imagem 3D | Alpine Wallpaper | Unknown Software | Unknown Developer |
| .APPS | Apple | Ficheiros de Dados | Golden Orchard Apple II CD Rom File | Unknown Software | Unknown Developer |
| .ARCH | Unknown Developer | Ficheiros de Dados | Illum Source Dotfiles File | Unknown Software | Unknown Developer |
| .ARMOURFONT | Apple | Ficheiros de Dados | Golden Orchard Apple II CD Rom File | Unknown Software | Unknown Developer |
| .ASXP | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .AT | Unknown Developer | Uncommon Files | Rescue Disk File | Unknown Software | Unknown Developer |
| .ATOS | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .ATW | Unknown Developer | Ficheiros de Dados | Attityd Survey Program Data | Unknown Software | Unknown Developer |
| .AUDIO | Apple | Ficheiros de Dados | Golden Orchard Apple II CD Rom File | Unknown Software | Unknown Developer |
| .AW_ | Unknown Developer | Ficheiros Compactados | Midiprg Quartz Sets Compressed File | Unknown Software | Unknown Developer |
| .AYA | Unknown Developer | Uncommon Files | Uncommon File Extension | Unknown Software | Unknown Developer |
| .AYE | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .AZX | Unknown Developer | Ficheiros de Áudio | ZX Audio File Format | Unknown Software | Unknown Developer |
| .A_T | Unknown Developer | Ficheiros de Dados | Atrain File | Unknown Software | Unknown Developer |
| .B1N | Unknown Developer | Uncommon Files | Binary Screen Image File | Unknown Software | Unknown Developer |
| .B2Z | Unknown Developer | Ficheiros de Dados | B2Z dVS Model/Object | Unknown Software | Unknown Developer |
| .B5B5 | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .B7S | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .BAI | B2W Software | Ficheiros Plugin | BUILD2WIN Add-in | Unknown Software | Unknown Developer |
| .BAI2 | Bank Administration Institute (BAI) | Ficheiros de Dados | Cash Management Balance Reporting Specifications Version 2 | Unknown Software | Unknown Developer |
| .BALL | Apple | Ficheiros de Dados | Golden Orchard Apple II CD Rom File | Unknown Software | Unknown Developer |
| .BANNER | Apple | Ficheiros de Dados | Golden Orchard Apple II CD Rom File | Unknown Software | Unknown Developer |
| .BAO | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .BATH | Apple | Ficheiros de Dados | Golden Orchard Apple II CD Rom File | Unknown Software | Unknown Developer |
| .BBZ | BitBlaze | Ficheiros de Áudio | Bitblaze Audio File | Unknown Software | Unknown Developer |
| .BCS | The Wavelength | Ficheiros de Configurações | Batch Compiler Specification File | Unknown Software | Unknown Developer |
| .BDCFG | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .BDIFF BUPDATE BINARY UPDATE | Unknown Developer | Ficheiros de Dados | Bdiff Bupdate Binary Update | Unknown Software | Unknown Developer |
| .BDMB | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .BDSM | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .BDU | Unknown Developer | Uncommon Files | Uncommon File Extension | Unknown Software | Unknown Developer |
| .BDZ | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .BEACON | Apple | Ficheiros de Dados | Golden Orchard Apple II CD Rom File | Unknown Software | Unknown Developer |
| .BEAT | Apple | Ficheiros de Dados | Golden Orchard Apple II CD Rom File | Unknown Software | Unknown Developer |
| .BEATWAVE | Apple | Ficheiros de Dados | Golden Orchard Apple II CD Rom File | Unknown Software | Unknown Developer |
| .BER | Unknown Developer | Uncommon Files | German Bericht Report File | Unknown Software | Unknown Developer |
| .BF4 | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .BFAB | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .BFCE | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .BFH | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .BFN | Brother International Corporation | Ficheiros de Fonte | Brother Embroidery Software Font | Unknown Software | Unknown Developer |
| .BHB | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .BIG | Electronic Arts | Ficheiros de Jogo | Electronic Arts Game Data File | Unknown Software | Unknown Developer |
| .BILL | Apple | Ficheiros de Dados | Golden Orchard Apple II CD Rom File | Unknown Software | Unknown Developer |
| .BIN | Unknown Developer | Ficheiros de Imagem de Disco | Binary Disk Image File | Unknown Software | Unknown Developer |
| .BJD | NDDigital | Ficheiros de Dados | NDDigital Print Bureau File | Unknown Software | Unknown Developer |
| .BKG | Samsung Electronics | Ficheiros de Dados | Samsung Document | Unknown Software | Unknown Developer |
| .BKH | Unknown Developer | Uncommon Files | Uncommon File Extension | Unknown Software | Unknown Developer |
| .BKL | KeyCarbon | Ficheiros de Dados | KeyCarbon Binary Keystroke Log | Unknown Software | Unknown Developer |
| .BKT | Zortech | Uncommon Files | Zortech Data File | Unknown Software | Unknown Developer |
| .BLACK | Apple | Ficheiros de Dados | Golden Orchard Apple II CD Rom File | Unknown Software | Unknown Developer |
| .BLI | Thomson Reuters Corporation | Uncommon Files | Thomson Speedtouch Firmware File | Unknown Software | Unknown Developer |
| .BLOCK | Apple | Ficheiros de Dados | Golden Orchard Apple II CD Rom File | Unknown Software | Unknown Developer |
| .BLOSSOMS | Apple | Ficheiros de Dados | Golden Orchard Apple II CD Rom File | Unknown Software | Unknown Developer |
| .BLURB | Apple | Ficheiros de Dados | Golden Orchard Apple II CD Rom File | Unknown Software | Unknown Developer |
| .BM_ | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .BNN | Unknown Developer | Ficheiros Gráficos | Vectorial Image File | Unknown Software | Unknown Developer |
| .BN_ | Unknown Developer | Uncommon Files | Ntgraph Ze32v215 File | Unknown Software | Unknown Developer |
| .BOA | Unknown Developer | Ficheiros Compactados | BOA Constrictor Compressed Archive | Unknown Software | Unknown Developer |
| .BONGO | Apple | Ficheiros de Dados | Golden Orchard Apple II CD Rom File | Unknown Software | Unknown Developer |
| .BOR | Apple | Ficheiros de Dados | Golden Orchard Apple II CD Rom File | Unknown Software | Unknown Developer |
| .BP | Data Access Worldwide | Ficheiros de Desenvolvedor | DataFlex Business Process Object | Unknown Software | Unknown Developer |
| .BPG | Open Source | Ficheiros de Imagem Raster | Better Portable Graphics (BPG) Image | Unknown Software | Unknown Developer |
| .BPU | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .BRHQUJL | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .BRUSH | Xerox | Ficheiros de Imagem Raster | Xerox Doodle Brush Bitmap Image | Unknown Software | Unknown Developer |
| .BTX | SmartWare Corporation | Ficheiros de Cópia de Segurança | SmartWare Backup Text File | Unknown Software | Unknown Developer |
| .BUF | Unknown Developer | Ficheiros Temporários | Buffer File | Unknown Software | Unknown Developer |
| .BUSH | Apple | Ficheiros de Dados | Golden Orchard Apple II CD Rom File | Unknown Software | Unknown Developer |
| .BUTTHEREIS | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
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