Common criteria is an ISO standard product evaluation which includes ITSEC and TCSEC.
CC evaluates the protection profiles (PPs) and security targets.
EAL 1 Functionally tested, all the threats to security are not seen as serious.
EAL 2 Structurally tested, low to moderate level of independently guaranteed security..
EAL 3 Methodically tested and checked, moderate level of independently ensured security.
EAL 4 Methodically designed, tested and reviewed. Developers or users require a moderate to high level of independntly ensured security.
EAL 5 Semiformally designed and tested, the requirement is hight level of independently ensured security.
EAL 6 Semiformally verified, designed and tested, for hight risk situations.
EAL 7 Formally verified, designed and tested, for extremelly high risk situations.