5 U.S.C. § 5708. Effect on other statutes

This subchapter does not modify or repeal—

1. (1)
   (1)any statute providing for the traveling expenses of the President;
2. (2)
   (2)any statute providing for mileage allowances for Members of Congress;
3. (3)
   (3)any statute fixing or permitting rates higher than the maximum rates established under this subchapter; or
4. (4)
   (4)any appropriation statute item for examination of estimates in the field.