ASHRAE Standard 70 was first published in 1972 and was revised in 1991 and again in 2006. This 2023 edition of the standard updates the 2006 edition by covering a broader range of air-device types and sizes, by specifying commercially available test instruments that have increased accuracy, by defining test facilities and installation procedures to better reflect the device under investigation at its intended application, and by clarifying methods of calculating test data so that they apply to the broader range of air devices now available in the market, including displacement ventilation and underfloor outlets.