FIXsession: admin35=2
Sent by either side when an incoming MsgSeqNum is higher than expected, asking for the messages in the gap. The counterparty answers either with the original messages carrying PossDupFlag=Y, or with a Sequence Reset carrying GapFillFlag=Y for administrative messages it will not replay. Expect one whenever a client reconnects to an existing session without resetting sequence numbers.
Direction: Either direction
First message sequence number to retransmit.Format: Sequence number of the first message to retransmit.
Last message sequence number to retransmit. Zero requests everything from BeginSeqNo onwards.Format: Sequence number, or 0 to request everything from BeginSeqNo onwards.
