This part of ISO 14577 specifies the method of verification and calibration of testing machines for carrying out the instrumented indentation test in accordance with ISO 14577-1:2015.It describes a direct verification method for checking the main functions of the testing machine and an indirect verification method suitable for the determination of the repeatability of the testing machine. There is a requirement that the indirect method be used in addition to the direct method and for the periodic routine checking of the testing machine in service.It is a requirement that the indirect method of verification of the testing machine be carried out independently for each test method.This part of ISO 14577 is also applicable for transportable testing machines.