This part of ISO 6508 specifies two separate methods - direct and indirect - of verification of testing machines for determining Rockwell hardness in accordance with ISO/DIS 6508-1:2012, together with a method for verifying Rockwell hardness indenters. The direct verification method is used to determine whether the main parameters associated with the machine function - such as applied force, depth measurement, and testing cycle timing - fall within specified tolerances. The indirect verification method uses a number of calibrated reference hardness blocks to determine how well the machine can measure a material of known hardness The indirect method may be used on its own for periodic routine checking of the machine in service. If a testing machine is also to be used for other methods of hardness testing, it shall be verified independently for each method. This part of ISO 6508 is applicable to stationary and portable hardness testing machines. Attention is drawn to the fact that the use of hardmetal for ball indenters is considered to be the standard type of Rockwell indenter ball. Steel indenter balls may continue to be used only when complying with ISO/DIS 6508-1:2012, Annex A.