1. A functional unit that can only process data of a single security level at a particular time. [2382-pt.8] 2. [An] information system (IS) device not trusted to properly maintain and separate data to different security levels. [INFOSEC-99]3.A device that is used to process data of a single security level at any one time. Since the device need not be trusted to separate data of different security levels, sensitivity labels do not have to be stored with the data being processed [TCSEC].