ISO 3801:1977

For some fabrics, mass per unit length and mass per unit area are related simply by the width of the fabric, but for other fabrics variations in structure may introduce an important distinction between mass per unit length and mass per unit area. The methods are applicable to woven fabrics (including those of "stretch" type) made up full width or folded down the middle, and apply to the determination of the fabric mass of complete pieces as well as of sample length.