Except as provided in sections
4181 and
4182 of this title, this chapter may not be construed to affect the validity of any right, duty, or obligation of the United States or other person arising under or pursuant to any commitment or agreement lawfully entered into before October 1, 1997, under the United States Housing Act of 1937 [
42 U.S.C.
1437 et seq.], subtitle D of title IV of the Cranston-Gonzalez National Affordable Housing Act [
42 U.S.C.
12899 et seq.], title II of the Cranston-Gonzalez National Affordable Housing Act [
42 U.S.C.
12721 et seq.], title IV of the McKinney-Vento Homeless Assistance Act [
42 U.S.C. 11360 et seq.], or section 2 of the HUD Demonstration Act of 1993.