AATCC 20-2018 describes the physical, chemical, and microscopical techniques for identifying textile fibers used commerically in the United States. Fibers may be examined in raw fiber form or taken from yarn or fabric. These test methods may be used to identify generic fiber types as defined by the Textile Fibers Products Identification Act and subsequent rules and regulations of the Federal Trade Commission. Quantitative methods for determining percentages in blends of fibers are covered by AATCC Test Method 20A, Fiber Analysis: Quantitative.