12 U.S. Code § 4563 - Multifamily special affordable housing goal
The Director shall, by regulation, establish a single annual goal, by either unit or dollar volume, of purchases by each enterprise of mortgages on multifamily housing that finance dwelling units affordable to low-income families.
When establishing the goal under this section, the Director shall establish additional requirements for the purchase by each enterprise of mortgages on multifamily housing that finance dwelling units affordable to very low-income families.
The Director shall require each enterprise to report on the purchase by each enterprise of multifamily housing of a smaller or limited size that is affordable to low-income families, which may be based on multifamily projects of 5 to 50 units (as such numbers may be adjusted by the Director) or on mortgages of up to $5,000,000 (as such amount may be adjusted by the Director), and may, by regulation, establish such aditional  requirements related to such units.
The Director shall monitor the performance of each enterprise in meeting the goals established under this section and shall evaluate such performance (for purposes of section 4566 of this title) based on whether the rent levels are affordable. A rent level shall be considered to be affordable for purposes of this subsection for low-income families if it does not exceed 30 percent of the maximum income level of such income category, with appropriate adjustments for unit size as measured by the number of bedrooms.
The Director shall determine, for each year that the housing goal under this section is in effect pursuant to section 4561(a) of this title, whether each enterprise has complied with such goal and the additional requirements under subsection (a)(2).
 So in original.