17 CFR 140.21 - Definitions.
(a)Classified information. Information or material that is:
(3) So designated.
(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.