Historically significant records

Definition
Historically significant records (also records or materials of extraordinary public interest) are records or materials that demonstrate and record the national security policies, actions, and decisions of the United States, including (1) policies, events, actions, and decisions that led to significant national security outcomes; and (2) the development and evolution of significant United States national security policies, actions, and decisions. These records will provide a significantly different perspective in general from records and materials publicly available in other historical sources and would need to be addressed through ad hoc record searches outside any systematic declassification program established under Executive Order.

Source

 * Public Interest Declassification Board enabling legislation, Pub. L. No. 106-657, section 709.