This standard establishes the conditions for the verification of the machines used to determine Rockwell hardness (ABCDEFGHK scales) in accordance with the UNE 7-424 standard. This standard describes a direct method to verify the main functions of the machine and an indirect method for the overall verification of the machine. The latter is only applicable when a routine periodic check of machines in service is carried out. If the testing machine is generally used for testing by other hardness methods, it should be verified separately for each method.