N.Y.C. Admin. Code § 27-248: § 27-248 Classification.

Buildings and spaces shall be classified in the mercantile occupancy group when they are used for display and sales of goods accessible to public inspection. Highly combustible or flammable goods, such as those made of pyroxylin products, shall be limited to small quantities that do not constitute a high hazard; if not so limited, the occupancy shall meet the requirements for high hazard occupancies when the latter are more restrictive than the corresponding requirements for the mercantile classification.