| xfm | Adobe Audition XFM Plug-in |
| xia | Chiasmus Encrypted File |
| xis | Chiasmus Key File |
| xl3 | Vegaelec XL3 System Data |
| xlnk | XML Link |
| xlsenx | Egis Encrypted Data |
| xmd | Bitdefender Plugin |
| xmo | Adobe Authorware Movie Driver |
| xmsc | FileMaker Pro XML Export Script |
| xmss | FileMaker Pro XML Script |
| xmwx | ExamSoft SofTest Working Data |
| xnk | Microsoft Exchange Public Folder Shortcut |
| xpt | Mozilla Firefox XPCOM Type Library |
| xpx | XPRafts Macro |
| xrnx | Renoise Tool |
| xrs | Real Player External Resource |
| 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 |
| yti | Google Picasa Plugin |
| yxwz | Alteryx Designer Analytic App |
