> ## Documentation Index
> Fetch the complete documentation index at: https://docs.kraken.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Sequence Reset

> Gap fill or hard reset of sequence numbers

<div className="api-banner">
  <span className="api-protocol fix">FIX</span>
  <span className="api-detail">session: drop copy</span>
  <span className="api-tag">35=4</span>
</div>

With GapFillFlag=Y this stands in for messages that will not be resent and MsgSeqNum remains meaningful. With GapFillFlag=N it is a hard reset: the counterparty jumps to NewSeqNo and ignores MsgSeqNum.

**Direction:** Either direction

***

<ResponseField name="header" type="" required>35=`4`</ResponseField>

<ResponseField name="123 - GapFillFlag" type="boolean">
  Whether this is a gap fill, in which case MsgSeqNum stays valid, or a hard sequence reset.

  **Possible values:**

  * `Y` : Gap fill - this SequenceReset stands in for messages that will not be resent; MsgSeqNum stays valid.
  * `N` : Hard sequence reset - ignore MsgSeqNum and jump to NewSeqNo.
</ResponseField>

<ResponseField name="36 - NewSeqNo" type="SeqNum" required>
  Sequence number the counterparty should expect next.
</ResponseField>

<ResponseField name="trailer" type="" required />