| StandardHeader | 1024 | | Each administrative or application message is preceded by a standard header. The header identifies the message type, length, destination, sequence number, origination point and time. TTwo fields help with resending messages. The PossDupFlag is set to Y when resending a message as the result of a session level event (i.e. the retransmission of a message reusing a sequence number). The PossResend is set to Y when reissuing a message with a new sequence number (e.g. resending an order). The receiving application should process these messages as follows: PossDupFlag—if a message with this sequence number has been previously received, ignore message, if not, process normally.PossResend—forward message to application and determine if previously received (i.e. verify order id and parameters).
The following table provides examples regarding the use of SenderCompID, TargetCompID, DeliverToCompID, and OnBehalfOfCompID when using a single point-to-point FIX session between two firms. Assumption (A=sellside, B =buyside): | SenderCompID | OnBehalfOfCompID | TargetCompID | DeliverToCompID |
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| A to B directly | A | | B | | | B to A directly | B | | A | |
The following table provides examples regarding the use of SenderCompID, TargetCompID, DeliverToCompID, and OnBehalfOfCompID when using a single FIX session to represent multiple firms. Assumption (A=sellside, B and C=buyside, Q=third party): | | SenderCompID | OnBehalfOfCompID | TargetCompID | DeliverToCompID | OnBeahlfOfSendingTime |
|---|
| Send from A to B via Q | | | | | | | | 1) | A sends to Q | A | | Q | B | | | 2) | Q sends to B | Q | A | B | | A’s SendingTime | | B responds to A via Q | | | | | | | | 1) | B sends to Q | B | | Q | A | | | 2) | Q sends to A | Q | B | A | | B’s SendingTime | | Send from A to B *AND* C via Q | | | | | | | | 1) | A sends to Q | A | | Q | B | | | 2) | Q sends to B | Q | A | B | | A’s SendingTime | | 3) | A sends to Q | A | | Q | C | | | 4) | Q sends to C | Q | A | C | | A’s SendingTime | | B *AND* C send to A via Q | | | | | | | | 1) | B sends to Q | B | | Q | A | | | 2) | Q sends to A | Q | B | A | | B’s SendingTime | | 3) | C sends to Q | C | | Q | A | | | 4) | Q sends to A | Q | C | A | | C’s SendingTime |
| Added FIX.2.7
Updated FIX.4.2 |
| StandardTrailer | 1025 | | Each message, administrative or application, is terminated by a standard trailer. The trailer is used to segregate messages and contains the three digit character representation of the Checksum value. | Added FIX.2.7 |
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