GB/T 23144-2023 "Paper and board — Determination of bending stiffness — General principles for two-point, three-point and four-point methods" is applicable to the determination of bending stiffness for various types of paper and paperboard. It clarifies the general principles of the three testing methods: two-point, three-point, and four-point methods. The two-point and three-point methods are suitable for thinner paper and paperboard, while the four-point method is applicable to corrugated board and thicker paperboard. The standard includes a two-point bending method and recommended specimen dimensions for the four-point method, defines bending stiffness, provides calculation formulas and requirements for testing instruments, and standardizes testing procedures and result presentation.