The purpose of this part is to—

(a) Preserve and retain to the maximum extent practicable as housing affordable to low income families or persons those privately owned dwelling units that were produced for such purpose with Federal assistance, without unduly restricting the owners' prepayment rights;

(b) Minimize the involuntary displacement of tenants currently residing in such housing;

(c) Work in partnership with State and local government and the private sector in the provision and operation of housing that is affordable to very low, low and moderate income families; and

(d) Facilitate the sale of housing to residents under a resident homeownership program.