This is a unique sequence identifier assigned to a given EAP session start or end event, sent with the SNMPv3 Inform notification. Because the EAP access point may resend an Inform if it doesn't receive an acknowledgement, the receiver uses this sequence number to detect and discard duplicate Informs for the same event. For example, if the access point retransmits an Inform after a timeout, both copies would carry the same ubpNotifyEAPSignalSequenceNumber value, letting the management station recognize the second as a duplicate.