| xdc | DarkCryptTC XDC Encrypted Container |
| xef | WinAce Encrypted Archive |
| xpa | Akai MPC Software Project Archive |
| xpak | XLN Audio Package |
| xpi | Mozilla XPInstall Package |
| xpku | Mac OS X Universal Binary Package |
| xrec | xRecovery Data |
| xsa | XelaSoft Archive |
| xsoem | XenServer OEM Update Archive |
| xsupdate | XenServer Update Archive |
| xz | XZ Compressed File |
| xzm | Porteus Module |
| yar | YAK Compressed Archive |
| yaz0 | YAZ0 Compressed Archive |
| ybs | YBS Compressed Archive |
| yc | YAC Compressed |
| yep | Yamaha Expansion Pack |
| yz | YAC Compressed |
| yz1 | DeepFreezer Archive |
| z | Compressed File |
| z00 | InfoZIP ZipSplit Splitted ZIP Archive |
| z01 | InfoZIP ZipSplit Splitted ZIP Archive |
| z01 | WinZip First Split Zip |
| z02 | InfoZIP ZipSplit Splitted ZIP Archive |
| z02 | WinZip First Split Zip |
| z03 | InfoZIP ZipSplit Splitted ZIP Archive |
| z03 | WinZip First Split Zip |
| z04 | InfoZIP ZipSplit Splitted ZIP Archive |
| z04 | WinZip First Split Zip |
| z05 | InfoZIP ZipSplit Splitted ZIP Archive |
