This European Standard applies to distributor valves and distributor-isolating devices. The distributor valves contained in this European Standard are of graduated release type. Direct release types are not included. Functionally they are regarded as not containing relay valves of any type, even if the relay valves are physically an integral part of the distributor valves. This European Standard applies to both distributor-isolating devices mounted separate from the distributor valve and distributor-isolating devices integral with the distributor valve. This European Standard specifies the requirements for the design, testing and quality assurance of distributor valves and distributor-isolating devices. For interoperable freight wagons, these devices which are operated by compressed air according to EN 14198 are assessed according to the respective technical specification of interoperability.