This part of ISO 12625 specifies a test method for the determination of the tensile strength of perforated lines of tissue paper. It uses a tensile-testing apparatus operating with a constant rate of elongation. This method is only used for measuring machine-direction tensile strength, that is for cross-direction perforations on tissue paper. The calculation of perforation efficiency is also specified in this part of ISO 12625. It is expressly stated that the detection of impurities and contraries in tissue paper and tissue products can be carried out according to ISO 15755. For the determination of moisture content in tissue paper and tissue products, ISO 287 can be applied.