Section 140.21 - Definitions(a)Classified information. Information or material that is:(1) Owned by, produced for or by, or under control of the United States Government, and(2) Determined pursuant to Executive Order 12356 or prior or succeeding orders to require protection against unauthorized disclosure, and(b)Compromise. The disclosure of classified information to persons not authorized access thereto.(c)Custodians. An individual who has possession of or is otherwise charged with the responsibility for safeguarding or accounting for classified information.(d)Classification levels. Refers to Top Secret "(TS)", Secret "(S)", and Confidential "(C)" levels used to identify national security information. Markings "For Official Use Only," and "Limited Official Use" shall not be used to identify national security information.48 FR 15464, Apr. 11, 1983