| wxm | wxMaxima Batch File |
| wxn | Waixing NES ROM Image |
| wzmul | WinZip Registration |
| xe | XMOS Executable |
| xensearch | XenCenter Saved Search |
| xeo | Signwave Auto-Illustrator Extension |
| xfm | Adobe Audition XFM Plug-in |
| xia | Chiasmus Encrypted File |
| xis | Chiasmus Key File |
| xlnk | XML Link |
| xlsenx | Egis Encrypted File |
| xlx | XoloX File |
| xmwx | ExamSoft SofTest Working Data |
| xnk | Microsoft Exchange Public Folder Shortcut |
| xpt | Mozilla Firefox XPCOM Type Library |
| xrs | Real Player External Resource |
| xslic | XenServer License Data |
| xtea | XTEA Encyrpted Data |
| xtra | Adobe Director Xtra Extension |
| xuv | BlueFlash Firmware Image |
| xxc | Centraline COACH Controller Firmware |
| ybd | YobiDrive Link |
| yenc | yEnc Encoded File |
| ymp | YaST Meta Package |
| ync | yEnc Encoded File |
| yps | Yahoo! Messenger Data |
| yti | Google Picasa Plugin |
| z1 | ZoneAlarm Renamed VB |
| zfsendto | Windows Compressed Folder Shortcut |
| zgi | Zoomerang Web Survey Page |
