NT is a single level system, so this means that it can be used to deal with any level of data classification, but only that level.

So if it has been labeled a secret system. It can only have data (objects) and users (subjects) labeled as secret. This is inclusive of all system components.

Essentially this means that the system access must be controlled by a multi-level secure (MLS) processor if you want this machine to access data of different levels. To say it is verified to deal with classified data is rather misleading, although it does have an assurance rating of 2 under the TCSEC so it is good enough for secure environments. (Linux in all thus far evaluated manners would only score an assurance rating of 1, though Linux has only been evaluated against ISO-15408 and not the TCSEC.)

cheers,

catch