http://www.rfc-editor.org/rfc/rfc1172.txt
RFC 1172: Point-to-Point Protocol (PPP) initial configuration options, D. Perkins, R. Hobby1990-07-01T23:00:00-00:00This memo specifies the Point-to-Point Protocol (PPP) Initial Configuration Options as a Proposed Standard Protocol for the Internet community. When it becomes a full Standard, this protocol will be recommended for all TCP/IP implementations that communicate over serial links.