Real Decreto número 656/89 de 02/06/1989, por el que se aprueban los métodos de análisis cuantitativos de mezclas binarias y terciarias de fibras textiles. Boletín Oficial del Estado número 142 de 15/06/1989 Página 18396

This Spanish Royal Decree establishes standardized methods for the quantitative analysis of binary and tertiary mixtures of textile fibers. It ensures that the composition of blended fabrics can be accurately measured and verified. The regulation affects the textile industry, manufacturers, and quality control laboratories in Spain. It provides the technical framework necessary to certify the fiber content of textile products.