For the purpose of this subchapter—
(1)
“agency” means—
(C)
the Library of Congress;
(D)
the Government Printing Office; and
(E)
the government of the District of Columbia;
(2)
“employee” means an individual employed in or under an agency;
(3)
“head of each agency” means—
(A)
the Director of the Administrative Office of the United States Courts with respect to the judicial branch; and
(B)
the Mayor of the District of Columbia with respect to the government of the District of Columbia; and
(4)
“United States”, when used in a geographical sense, means the several States and the District of Columbia.