multilevel security (MLS)

1. [The] concept of processing information with different classifications and categories that simultaneously permits access by users with different security clearances and denies access to users who lack authorization. [INFOSEC-99] 2. A system operating in this mode is one which stores and/or processes data at various classifications etc, but for which there are users not cleared for or who need to know about all the data and whose access is restricted appropriately [CESG]. See also: Dedicated Security Mode, System High Security Mode, Compartmented Security Mode.