Sequence Reset (MsgType = 4)

The Sequence Reset (4) message is used by the sending application to reset the incoming sequence number on the opposing side. The Sequence Reset (4) message can be used in the following situations

The sending application will initiate the sequence reset. The message is used to reset the value of the next sequence number to be transmitted.

If the GapFill (123) field is not present (or set to N), it can be assumed that the purpose of the sequence reset message is to recover from an out-of-sequence condition, therefore, the MsgSeqNum (34) in the header should be ignored (i.e. the receipt of a sequence reset message with an out of sequence MsgSeqNum (34) should not generate resend requests).

If the GapFill (123) field is present (and equal to Y), the MsgSeqNum (34) should conform to standard message sequencing rules.

The sequence reset can only increase the sequence number; if a sequence reset is received attempting to decrease the next expected sequence number the message should be rejected and treated as a serious error.

Tag Field Name FIXML Req'd Comments
<Standard Message Header> Y MsgType = 4
123 GapFillFlag N
36 NewSeqNo Y
<Standard Message Trailer> Y