This International Standard specifies, in order to ensure interchangeability, the dimensions and other characteristics of surfaces on which hydraulic pressure-reducing valves, sequence valves, unloading valves, throttle valves and check valves are mounted.

It is applicable to mounting surfaces for hydraulic pressure-reducing valves, sequence valves, unloading valves, throttle valves and check valves, which represent current practice. They are generally used in industrial equipment.