This subchapter does not modify or repeal—
(1) any statute providing for the traveling expenses of the President;
(2) any statute providing for mileage allowances for Members of Congress;
(3) any statute fixing or permitting rates higher than the maximum rates established under this subchapter; or
(4) any appropriation statute item for examination of estimates in the field.
(Pub. L. 89–554, Sept. 6, 1966, 80 Stat. 500.)