This part of IEC 62488 applies to power line carrier terminals and networks used to transmit information over power networks including extra high, high and medium voltage (EHV/HV/MV) power lines using both digital and optionally analogue modulation systems in a frequency range between 16 kHz and 1MHz (see also IEC 62488-1). In many countries, power line carrier (PLC) channels represent a significant part of the utility- owned telecommunication system. A circuit normally routed via a PLC channel can also be routed via a channel using a different transmission medium such as point to point radio, optical fibre or open wire circuit. It is therefore important that the input and output interfaces that are used between terminals in the communication system are standardised. The issues requiring consideration of DPLC and/or APLC devices as parts of a telecommunication network can be found in IEC 62488-1. Figure 1 shows the correspondence between the elements needed to implement PLC systems and the related International Standards.