This part of ISO 1924 specifies a method for measuring the tensile strength, strain at break and tensile energy absorption of paper and board, using a testing machine operating at a constant rate of elongation (20 mm/min). This part of ISO 1924 also specifies equations for calculating the tensile index, the tensile energy absorption index and the modulus of elasticity. Testing in conformance with this part of ISO 1924 always includes the measurement of tensile strength. Measurement or calculation of other properties is subject to agreement between the parties concerned. This part of ISO 1924 is applicable to all papers and boards, including papers with a high strain at break if the results are within the capacity of the testing machine. It also applies to the components of corrugated board but not, however, to corrugated board itself. This part of ISO 1924 is not applicable to tissue paper and tissue products for which ISO 12625-4 is applicable. For the determination of tensile properties of laboratory sheets, ISO 5270 is recommended.