Value,Description,Reference,Notes 0,Invalid,, 1,Request,[RFC1058], 2,Response,[RFC1058], 3,TraceOn,[RFC1058], 4,TraceOff,[RFC1058], 5,Reserved,[RFC1058], 6,Triggered Request,[RFC1582],"There are widely deployed implementations that don't support Triggered UDP that use value 6 = ""Poll Entry"" (undocumented)" 7,Triggered Response,[RFC1582], 8,Triggered Acknowledgement,[RFC1582], 9,Update Request,[RFC2091], 10,Update Response,[RFC2091], 11,Update Acknowledge,[RFC2091], 12-254,Unassigned,,