http://www.rfc-editor.org/rfc/rfc1764.txt
RFC 1764: The PPP XNS IDP Control Protocol (XNSCP), S. Senum1995-03-01T23:00:00-00:00This document defines the Network Control Protocol for establishing and configuring the Xerox Network Systems (XNS) Internet Datagram Protocol (IDP) over PPP. [STANDARDS-TRACK]