N.Y.C. Admin. Code § 26-505: § 26-505 Application to multiple family complex.

For purposes of this chapter a class A multiple dwelling shall be deemed to include a multiple family garden-type maisonette dwelling complex containing six or more dwelling units having common facilities such as sewer line, water main, and heating plant, and operated as a unit under a single ownership on May sixth, nineteen hundred sixty-nine, notwithstanding that certificates of occupancy were issued for portions thereof as one- or two-family dwellings.