Session-Level Messages

Sequence Reset <4>

The Sequence Reset <4> message is used in response to a Resend Request <2> message when one or more messages must be skipped over for the following reasons:

During normal resend processing, the sending application may choose not to send a message (e.g. an aged order).
During normal resend processing, a number of administrative messages are skipped and not resent (such as Heartbeat <0> and Test Request <1>).

Gemini does not support Reset mode (GapFillFlag <123> not present or equal to N).

Tag	Name	Req	Description
	Standard Header	Y	MsgType = `4`
36	NewSeqNo	Y	New sequence number. The receiver should expect this to be the sequence number of the following message.
123	GapFillFlag	Y	Indicates that the sender is skipping messages rather than resending them. Valid value: `Y` = Gap Fill message
	Standard Trailer	Y

Last modified on October 8, 2025