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50 U.S. Code § 834 - “Classified information” defined

For the purposes of this section, the term “classified information” means information which, for reasons of national security, is specifically designated by a United States Government agency for limited or restricted dissemination or distribution.

(Sept. 23, 1950, ch. 1024, title III, § 304, as added Pub. L. 88–290, Mar. 26, 1964, 78 Stat. 170.)