“Subchapter I of chapter 81 of title 5” substituted for reference to act Sept. 7, 1916 (39 Stat. 742), known as the Federal Employees’ Compensation Act, on authority of Pub. L. 89–554, § 7(b), Sept. 6, 1966, 80 Stat. 631, the first section of which enacted Title 5, Government Organization and Employees.