Header and Trailer
Every session-level and application-level message in both FIX APIs uses the same header and trailer. The message body between them contains the fields listed on that message’s reference page.
See FIX Message Layouts for ordering and presence rules.
Header
| Field | Type | Presence | Behavior |
|---|---|---|---|
BeginString(8) |
STRING |
Required | The session protocol version is BeginString(8)=FIXT.1.1 for both message levels. |
BodyLength(9) |
LENGTH |
Required | |
MsgType(35) |
STRING |
Required | |
SenderCompID(49) |
STRING |
Required | |
TargetCompID(56) |
STRING |
Required | |
MsgSeqNum(34) |
SEQNUM |
Required | |
PossDupFlag(43) |
BOOLEAN |
Optional | |
PossResend(97) |
BOOLEAN |
Optional | |
SendingTime(52) |
UTCTIMESTAMP |
Required | |
OrigSendingTime(122) |
UTCTIMESTAMP |
Conditional | Sent by the exchange on retransmissions and sequence-reset gap fills. Carries the original sending time. |
Trailer
| Field | Type | Presence | Behavior |
|---|---|---|---|
CheckSum(10) |
STRING |
Required |