| X-Mailer: | 3.10e |
| X-Newsreader: | 3.12e |
| X-No-Archive: | 4.8d |
| X-server | 19.9a |
| X-terminale | 19.9a 19.9c |
| X-URL: | 3.10e |
| X-Windows | 16.2m 19.9 |
| X-Windows, connessione via rete | 19.9c |
| X-Windows per Linux | 19.12c |
| X-Windows, window manager | 19.9b |
| XFer Pro | 16.10h |
| XFree86 | 19.12c |
| XingIt MpegView | 16.13c |
| Xref: | 3.12e |
| xterm | 19.9a |
| XXEncode | 16.10f |