This standard contains the introduction in the further parts of the series EN 50121 or DIN EN 50121 (VDE 0115-121), respectively, concerning the electromagnetic compatibility of railways and gives basic requirements. The requirements for railway applications are given in the further parts.In detail the performance criteria for immunity tests are specified and hints for the development of a EMC management plan are given. Annexe A contains general informations concerning the EMC of the railway system. In relation to the previous edition the undated references were changed into dated references and the references to 91/440/EWG and EN 50238 were deleted.