scope:

This pre-standard specifies limits for emission and immunity and provides performance criteria for signalling and telecommunications (S& T) apparatus which may interfere with other apparatus in the railway environment, or increase the total emissions for the railway environment beyond the limits defined in the appropriate standard, and so risk causing Electro-magnetic Interference (EMI) to apparatus outside the railway system (The railway system is described in ENV 50121-1). The specific provisions are to be used in conjunction with ENV 50121-1.