The current status of the attribute instance monitored by this nwtControlEntry. As new volumes, disks, adapters, etc. are added to the server, entries for the new instances of each monitored attribute will automatically be added to this table, using appropriate default values for thresholds etc. From time-to-time, volumes, disks, adapters, etc. may also be permanently removed from the server; however, the entries for those instances in this table, and any associated histories, will continue to exist. A value of 'valid' indicates that the instance defined by this nwtControlEntry is present in the server. A value of 'invalid' indicates that the instance defined by this nwtControlEntry is no longer present in the server. Any associated history data is still available.