These door operators are therefore part of hold-open systems. Requirements and tests for hold-open systems are not integral part of this standard. The technical progress has led to the realization of the function former door closing devices with automatic opening with now electro-mechanical drive systems that power-operate both the opening and the closing. The combination of traditional (hydraulic) door closing device with an operator for the opening process is not compelled but various construction types are possible, e. g.: - power-operated opening and closing, with a mechanical energy storage on stand by and providing the self-closing function; - power-operated opening and closing, with a mechanical energy storage running and providing the self-closing function; - power-operated open and close function with door closing devices with hydraulic damping. To reflect the changed state of the art this standard was revised and renamed.