; and (ii) stipulate a preemptive option to purchase the affordable rentals or homeownership units so that the affordability of the units is preserved for successive income-eligible households; and (B) monitor properties to ensure affordability is preserved. (4) Land bank The term land bank means a government entity, agency, or program, or a special purpose nonprofit entity formed by one or more units of government in accordance with State or local land bank enabling law, that has been designated by one or more State or local governments to acquire, steward, and dispose of vacant, abandoned, or other problem properties in accordance with locally determined priorities and goals. (5) Neighborhood revitalization support activity The term neighborhood revitalization support activity means an activity described in subsection (b)(3). (6) Non-performing mortgage The term non-performing mortgage means a residential mortgage loan that is 90 days or more delinquent. (7) Nonprofit organization The term nonprofit organization means an organization that is described in section 501(c)(3) of the Internal Revenue Code of 1986 ( 26 U.S.C. 501(c)(3) ) and is exempt from taxation under section 501(a) of such Code. (8) Shared equity homeownership program (A) In general The term shared equity homeownership program means affordable homeownership preservation through a resale restriction program administered by a community land trust, other nonprofit organization, or State or local government or instrumentalities. (B) Affordability requirements Any such program under subparagraph (A) shall— (i) provide affordable homeownership opportunities to households; and (ii) utilize a ground lease, deed restriction, subordinate loan, or similar legal mechanism that includes provisions ensuring that the program shall— (I) maintain the home as affordable for subsequent very low-, low-, or moderate-income families for an affordability term of at least 30 years after recordation