Two types of SAP exist: acknowledged and unacknowledged. The existence of an acknowledged SAP may be publicly disclosed, but the details of the program remain classified. An unacknowledged SAP (or USAP) is made known only to authorized persons, including members of the appropriate committees of the United States Congress. Waived SAPs are a subset of unacknowledged SAPs in the Department of Defense. These SAPs are exempt by statutory authority of the Secretary of Defense from most reporting requirements and, within the legislative branch, the only persons who are required to be informed of said SAPs are the chairpersons and ranking committee members of the Senate Appropriations Committee, Senate Armed Services Committee, House Appropriations Committee, and the House Armed Services Committee. Oftentimes, this notification is only oral.