| 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 |
| zipenx | Egis Encrypted File |
| zl0 | ZoneAlarm MailSafe Renamed ADE File |
| zl3 | ZoneAlarm MailSafe Renamed BAT File |
| zl4 | ZoneAlarm MailSafe Renamed CHM File |
| zl9 | ZoneAlarm MailSafe Renamed EXE |
| zli | ZoneAlarm MailSafe Renamed MDE File |
| zlj | ZoneAlarm MailSafe Renamed MSC File |
| zlk | ZoneAlarm MailSafe Renamed MSI File |
| zlo | ZoneAlarm MailSafe Renamed PIF |
| zlp | ZoneAlarm MailSafe Renamed REG File |
| zlq | ZoneAlarm MailSafe Renamed SCR |
