| xslic | XenServer License Data |
| xtea | XTEA Encyrpted Data |
| xtn | OSLib Program |
| xtnd | Adobe Acrobat for Mac Plug-in |
| xtra | Adobe Director Xtra Extension |
| xuv | BlueFlash Firmware Image |
| xxc | Centraline COACH Controller Firmware |
| xxe_addon | XMLmind XML Editor Add-on |
| ybd | YobiDrive Link |
| yenc | yEnc Encoded File |
| ymp | YaST Meta Package |
| ync | yEnc Encoded File |
| yps | Yahoo! Messenger Data |
| yti | Google Picasa Plugin |
| yxwz | Alteryx Designer Analytic App |
| z1 | ZoneAlarm Renamed VB |
| zfsendto | Windows Compressed Folder Shortcut |
| zg | Honeywell MP Compact4 Firmware |
| zgi | Zoomerang Web Survey Page |
| zgk | ZIPGenius Key Data |
| zipenx | Egis Encrypted Data |
| zl0 | ZoneAlarm MailSafe Renamed ADE File |
| zl1 | ZoneAlarm MailSafe Renamed ADP File |
| zl2 | ZoneAlarm MailSafe Renamed BAS File |
| zl3 | ZoneAlarm MailSafe Renamed BAT File |
| zl4 | ZoneAlarm MailSafe Renamed CHM File |
| zl5 | ZoneAlarm MailSafe Renamed CMD File |
| zl6 | ZoneAlarm MailSafe Renamed COM File |
| zl7 | ZoneAlarm MailSafe Renamed CPL File |
| zl8 | ZoneAlarm MailSafe Renamed CRT File |
