This document is limited to specifying the requirements when applying lubricants to the wheel-rail interface between the wheel flange and the rail gauge corner (active interface) either directly or indirectly to the wheel flange or to the rail, and includes both trainborne and trackside solutions. This document defines: - the characteristics that systems of lubrication of the wheel-rail interface shall achieve, together with applicable inspection and test methods to be carried out for verification; - all relevant terminology which is specific to the lubrication of the wheel-rail interface.