This part of EN 13674 specifies flat bottom symmetrical railway rails of 46 kg/m and greater linear mass, for general and high speed railway track usage. Seven pearlitic steel grades are specified giving a hardness range between 200-390 HBW. The rails are either non heat treated carbon manganese or alloy steel, or heat treated carbon manganese or low alloy steel. There are 21 rail profiles specified in this Standard. Two rail classes are specified, differing in requirements for straightness, surface flatness and crown profile. Three classes of profile tolerances are specified.