A prior section 523 of act July 1, 1944, was renumbered section 544 by section 611(2) of Pub. L. 100–77 and is classified to section 290dd–3 of this title.

1990—Pub. L. 101–645 amended section generally, substituting present provisions for provisions which related to: in subsec. (a), general requirements; and in subsec. (b), determination of amount of non-Federal contribution.