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The Whisperer Feed Handler validates the sequence number value as expected by the MFAPI client as follows:

• If the Client is expecting a sequence number higher than the FH's next-to-be-assigned msgSeqNum, then this is an unrecoverable error and the FH will abort the session with a Logout message.
• Otherwise the FH will issue a LogonResponse

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• message containing the next MsgSeqNum[34] value that it expects to receive from the client.
• If the Client is expecting a sequence number lower than the FH's next-to-be-assigned msgSeqNum[34], then the message gap is resolved by the FH with SequenceResetGapFill messages and the resending of persisted messages as necessary.

The Whisperer Feed Handler signals it's completion of session synchronisation with a TestRequest.

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After any inbound sequence number gaps have been resolved for the MFAPI Client, it then reciprocates in a similar manner, based on the the next MsgSeqNum[34] value that the Whisperer Feed Handler expects to receive from the client - as specified in it's LogonResponse.

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