This European Standard defines the interfaces and gives guidance for the design of systems and procedures for change of track gauge, covering also their assessment for technical approval, for the automatic variable-gauge systems. The standard is focused on the change of track gauge among the following nominal track gauges: 1435 mm, 1520 mm, 1524 mm, 1600 mm and 1668 mm. This document is not limited to the aforementioned nominal track gauges but the interfaces to change to/from other nominal track gauges can be different. The established assessment procedures can be used as well.