http://www.rfc-editor.org/rfc/rfc0861.txt
RFC 0861: Telnet Extended Options: List Option, J. Postel, J. Reynolds1983-05-01T23:00:00-00:00This Telnet Option provides a mechanism for extending the set of possible options. This RFC specifies a standard for the ARPA Internet community. Hosts on the ARPA Internet are expected to adopt and implement this standard. Obsoletes NIC 16239.