The White House, Executive Order 13142: Amendment to Executive Order 12958-Classified National Security Information, 64 Fed. Reg. 66089-66090 (Nov. 19, 1999) (full-text).
This Executive Order established the Information Security Oversight Office within the National Archives and Records Administration and extends and establishes specific dates for the time within which all classified information contained in records more than 25 years old that have been determined to have historical value should be automatically declassified. The Archivist of the United States delegates the implementation and monitorship functions of this program to the Director of the Information Security Oversight Office.