49 C.F.R. § 806.3 – Definitions.

(a) Classified information. Information or material, herein collectively termed information, that is owned by, produced for or by, or under the control of, the United States Government and that has been determined pursuant to Executive Order 12065, or prior orders, to require protection against unauthorized disclosure and that is so designated. One of the following classifications will be shown:
1. (1) Top secret means information, the unauthorized disclosure of which reasonably could be expected to cause exceptionally grave damage to the national security.
2. (2) Secret means information, the unauthorized disclosure of which reasonably could be expected to cause serious damage to national security.
3. (3) Confidential means information, the unauthorized disclosure of which reasonably could be expected to cause identifiable damage to the national security.
(b) Foreign government information means either: (1) Information provided to the United States by a foreign government or international organization of governments in the expectation, express or implied, that the information is to be kept in confidence; or (2) information produced by the United States pursuant to a written joint arrangement with a foreign government or international organization of governments requiring that either the information or the arrangements or both, be kept in confidence.
(c) National security means the national defense and foreign relations of the United States.
(d) Declassification event means an event which would eliminate the need for continued classification.