(A) The term challenge cost-share agreement means any agreement entered into between the Secretary and any cooperator for the purpose of sharing costs or services in carrying out authorized functions and responsibilities of the Secretary of the Interior with respect to any unit or program of the National Park System (as defined in section 1c (a) of this title), any affiliated area, or any designated National Scenic or Historic Trail.

(B) The term cooperator means any State or local government, public or private agency, organization, institution, corporation, individual, or other entity.