The FTP protocol is officially defined to use the telnet protocol as transport channel for the control connection. However, many implementations are broken and does not respect this aspect of the FTP protocol.
If there is any trouble accessing files with ASCII code 255 in the path or similar problems involving this ASCII code you can try setting this directive to off. If that helps, report to the operator of the FTP server in question that their FTP server is broken and does not follow the FTP standard.
Arguments