A technical and scientific society that developed the U.S. standard for assessing the level of UV protection provided by a fabric. The test method is known as AATCC TM 183. It is a laboratory test performed with specialized equipment, either a spectrophotometer or a spectroradiometer. The test covers both UVA and UVB. Results can be given as a percentage UV blocked or as a Ultraviolet Protection Factor (UPF).