This part of JIS K 7128 specifies a method of determining the force required to propagate a tear through a specified distance and from a specified slit, cut in a test specimen of thin flexible plastic sheeting or film, under specified conditions of loading. The upper limit of thickness that can be tested depends on the tearing force of the material in relation to the capacity of the testing machine. Materials that can be tested according to this method include flexible poly (vinylchloride) (PVC) and polyolefin films, but variable elongation and oblique tearing effects on the more extensible films may cause poor reproducibility of test results. This method may not be suitable for testing more rigid materials such as rigid PVC, nylon and polyester films.