This Part of prCEN/TS 13126 specifies the requirements and test methods for durability, strength, security and function of devices that restrict the opening of windows.The following types of restrictors are included:a) Restricted opening devices with or without friction systems;b) Hold open devices;c) Peg type casement stays;d) Maximum opening stops.It shall apply to all devices that restrict the opening of hinged and pivoted windows, whether the devices are products that may be fitted to a window separately from other operating fittings or whether the restricted opening is achieved by means of features in the design of fittings such as hinges or pivots.NOTE Safety in use could be affected by the failure of restricted opening devices that limit the initial opening of a window. Accordingly, such safety related devices are subjected to higher wind loads than hold-open devices or maximum opening stops. The durability test is not applicable to peg type casement stays.