With the continuing development of European standards (ENs), the content of the UIC leaflets (in this case UIC Leaflet 541-04, 4th edition) needs to be aligned with that of the ENs covering the same ground (in this case EN 15611, EN 15624 and EN 15625), in order to eliminate duplication and any deviation of content. Where justified, any content deviating from or additional to the relevant ENs is mentioned in the present UIC Leaflet 541-04, 4th edition.