Applicable to spun in use and folded yarns of any fibre or mixture of fibres manufactured by any spinning systems. Not it for testing filament yarns, glass yarns, the more complex structures to the as cabled yarns or cords. Not Applicable to those yarns having a diameter so great as to prevent the winding of the skein in two even the layers. - Replaces the first edition (ISO 6939:1982) and constitutes its minor revision.