N.Y. Comp. Codes R. & Regs. tit. 10 § 755.1
An ambulatory surgery service is a service organized to provide those surgical procedures which need to be performed for safety reasons in an operating room on anesthetized patients requiring a stay of less than 24 hours' duration. These procedures do not include those outpatient surgical procedures which can be performed safely in a private physician's office or an outpatient treatment room. Ambulatory surgery services may be provided in a free-standing ambulatory surgery center or a hospital-based ambulatory surgery center. Hospital-based ambulatory surgery centers may be on-site or off-site, as described in section 405.20 of this Title. The provisions of this Part shall be applicable to free-standing ambulatory surgery centers and off-site hospital-based ambulatory surgery centers.
N.Y. Comp. Codes R. & Regs. Tit. 10 § 755.1