FIX - Session Management

Header and Trailer

All FIX messages must begin with header fields and end with a trailer field.

Standard Header

TagField NameData TypeReq’dComments
8BeginStringstringYIdentifies beginning of new message and protocol version. Always the first field in a message. Value is FIX.4.4.
9BodyLengthintYMessage length, in bytes, forward to the CheckSum <10> field. Always second field in message and unencrypted.
35MsgTypestringYDefines message type. Always third field in message.
49SenderCompIDintYUsed to identify a firm which sends the message.
56TargetCompIDstringYUsed to identify a receiving firm.
34MsgSeqNumintYInteger message sequence number.
43PosDupFlagbooleanCRequired for retransmitted messages as a result of ResendRequest.
97PossResendbooleanCRequired when message may be a duplicate of another message sent under a different sequence number.
122OrigSendingTimetimestampCRequired for messages sent as a result of ResendRequest. Time of original transmission in UTC.
52SendingTimetimestampYTime of message transmission in UTC.

Standard Trailer

TagField NameData TypeReq’dComments
10CheckSumintYSimple checksum. Always defined as three characters in the last field in the message.