Specifies four methods for the determination of the hardness of vulcanized or thermoplastic rubbers on flat surfaces: normal test (N), high-hardness test (H), low-hardness test (L), microtest (M), and four methods for the determination of apparent hardness of curved surfaces using methods N, H, L and M, respectively (CN, CH, CL and CM). The methods differ primarily in the diameter of the indenting ball and the magnitude of the indenting force