This document specifies the classification, requirements, test methods, acceptance rules, marking, packaging, transportation and storage of flame-retardant sewing threads. This document applies to pure or blended inherently flame-retardant, permanent flame-retardant sewing threads and finishing flame-retardant sewing threads used in places with open flames, emitting sparks, or in places with flammable substances and risk of flashover. Other flame retardant sewing threads are available for reference.