| ate | Microsoft Accounting Accountants Transfer |
| ati | Microsoft Accounting Import |
| atlas | Exient XGS Atlas Archive |
| avastsounds | Avast Antivirus Sound Package |
| avasttheme | Avast Antivirus Theme Data |
| avgsounds | AVG Internet Security Sound Package |
| awb | CRIWARE AWB Package |
| awi | AIM Widget Package |
| aza | ProSystem fx Engagement Admin Package |
| azp | ProSystem fx Engagement Binder Package |
| b1 | B1 Compressed Archive |
| b6z | B6Zip Archive |
| ba | Scifer External Header Archive |
| baklz4 | Mozilla Firefox Compressed Backup |
| balz | BALZ Compressed Archive |
| bar | BlackBerry 10 Application Package |
| bbb | BlackBerry Mobile Phone Backup |
| bbtheme | phpBB Theme Package |
| bca | Jetico BCArchive Encrypted Archive |
| bcpio | Binary CPIO Archive |
| bee | BeeGui Bee Archiver Archive |
| bel | HPXView Binary Event Log Archive |
| bfa | Blowfish Advanced CS Encrypted File |
| bff | AIX Backup File Format |
| bh | BlakHole Archive |
| bhx | BinHex Encoded Archive |
| bio | BioArc Compressed Archive |
| bkc | Backup4all Backup Catalog |
| bkf | Windows NT Backup Archive |
| bko | BackupOutlook Backup Archive |
