This read-only enumerated value reports what went wrong during a router's management process: none(0), unexpected-serial-number(1), unexpected-hostname(2), connection-lost(3), or notification-received(4); per the description, a nonzero value while status shows managing(2) indicates something went wrong, and before management begins the value starts at connection-lost(3) and moves to notification-received(4) once the TIDP master hears from the target equipment. Admins check it to diagnose why a router entry stuck in a non-managing state hasn't come online, or to confirm a management attempt failed due to a mismatched identifier. A value of unexpected-serial-number(1) while status is managing(2) tells the admin the router that responded had a different serial number than the one configured for that entry, indicating a mismatch.