This standard defines the terms and their definitions (or the source if defined in other standards) necessary for describing pressure and temperature, dimensions, design, flow characteristics, operation and tests for valves. It aims to provide a uniform terminology for all types of valves. The terms and definitions in this standard may also apply to products other than valves, in which case it may be necessary to apply these definitions analogously. This standard covers terms common to more than one type of valve. The terms and definitions specific to one type of valve are found in the relevant product standard.