This document indicates the real definition of these terminolgies and then the administrator can you use the correct manage status.
2-Out of service.
Not Managed – Indicates the node is intentionally not managed. For example, the node might not be accessible because it is in a private network. NNMi does not update discovery information or monitor these nodes.
Out of Service – Indicates a node is unavailable because it is out of service. NNMi does not update discovery information or monitor these nodes.
You can find more details in the followign document http://support.microfocus.com/kb/kmdoc.php?id=KM00392971