This European standard defines the terms and their definitions (or the source if defined in other European standards) used for several types of valves or in several fields of application. These terms concern the pressures and temperatures, the dimensions, the design, the flow control characteristics and the test of valves. The terms and definitions in this European standard may also apply to products other than valves, in which case it may be necessary to apply these definitions analogously. This European standard covers terms common to more than one type of valve. The terms and definitions specific to one type of valve, or to one application are found in the relevant product standard or fitness for purpose standard.