(a) In general. Sections 1.401 through 1.401–14 (inclusive) reflect the provisions of section 401 prior to amendment by the Employee Retirement Income Security Act of 1974. The sections following §1.401–14 and preceding §1.402(a)–1 (hereafter referred to in this section as the "Post-ERISA Regulations") reflect the provisions of section 401 after amendment by such Act.