The following list of terms is used to indicate type, level, or scope of security clearance and background investigation in the United States.
Security clearance descriptors often appear in employment advertisements, as employers generally prefer to hire people who are already cleared to access classified information at the level needed for a particular job or contract.
Due to the nature of security classifications and clearances, often people incorrectly identify their clearances by a combination of actual clearance level, additional access controls, caveats, and the organization who granted them clearance. In addition, different organizations within the Federal government use different terminology and lettering, as is discussed below.
Some items on are based on a list compiled by a nonauthoritative source] on the Internet. Items marked "*" are defined in the 2006 U.S. Government's National Industrial Security Program Operating Manual (NISPOM) p. 14 ff Any combination of the SI, SI-ECI-*, B, G, HCS letters can be used.
Information is classified at 3 levels. For general access to this information, the Cognizant Security Authority ( Generally, the DoD), grants collateral clearances at the level: