The U.S. Government's (now obsolete) standards document Trusted Computer System Evaluation Criteria, DOD standard 5200.28-STD, December, 1985 which characterize secure computing architectures and defines levels A1 (most secure) through D (least). Modern Unixes are roughly C2. See also {book titles}.
[glossary]
[Reference(s) to this entry by made by: {book titles}{Multics}{rainbow series}{TCB}]