uch 'touch current' flowing through ENs, ETRs, ETSs and NETs should be available from national a person who touches the passive bus, due to the fact that the bus is standards organisations, especially in Europe. The English versions floating with respect to earth. ETR 12 will also list protection can be obtained from BSI, Linford Wood, Milton Keynes, MK14 requirements for each interface but this area needs further study. 6LE, UK. Clearly, unspecified compliance with EN 41003 should never be claimed or demanded. Table 23.2 IEC, ETSI and CENELEC publications With IEC 950, the situation is less simple because designers and specifiers often claim or specify total compliance with the standard. There is no superior standard defining which bits of IEC 950 do Title EN/HD apply. ETSI ETR 12 offers this information but it is a regional (European) document. IEC 950 itself tries to help by stating that an Publicatio interface connected to a Telecommunication Network must be a TNV circuit, but the definition of Telecommunication Network is Particular electrical very imprecise. Is a Local Area Network, or the ISDN passive bus, safety requirements for 41003 or a long analogue telephone cable entirely on a subscriber's equipment to be premises a telecommunication network? connected to There being no clear solution to this problem at present, there is a telecommunications need for flexibility, common sense and mutual understanding be- networks tween manufacturers, test houses and approval authorities. This is IEC 65 especially so where conformance with a standard is mandatory, and Safety requirement for where non-compliance can mean that permission to connect the box (mod) mains operated 195 S1 electronic and to a network cannot be obtained. related apparatus for Another area where rules need to be written and applied with household and practical understanding is that of the constant evolution of the similar use standards, and in particular the adoption of successive modifications of IEC 950 into EN 60950 by CENELEC. This adoptio