The Resend Request <2> message can be sent by either side to initiate the retransmission of messages. It can be used if a sequence number gap is detected, or if either side lost a message, or as a function of the initialization process.

Tag	Field Name	Data Type	Req’d	Comments
Standard header			Y	MsgType `35=2`
7	BeginSeqNo	int	Y	Sequence number of first message in range to be resent.
16	EndSeqNo	int	Y	Sequence number of last message in range to be resent. Set EndSeqNo to 0 if all messages subsequent to BeginSeqNo are required.
Standard trailer			Y