This is a standard TestAndIncr advisory lock that a management station reads and increments before issuing a SET operation, generating a unique identifier the agent can use to tag extended status information about that particular SET request. It exists to coordinate concurrent SNMP SET operations from multiple managers so each one can be tracked individually. For example, a management tool reads the current value, includes it incremented by one in its SET request, and then looks up the corresponding return-code entry keyed to that same value.