Не знаю точно, врать не буду. Но вот здесь можете почитать https://www.tadviser.ru/index.php/%D0%9F%D1%80%D0%BE%D0%B5%D0%BA%D1%82:%D0%93%D0%98%D0%A1_%D0%95%D0%A6%D0%A5%D0%94_(%D0%95%D0%B4%D0%B8%D0%BD%D1%8B%D0%B9_%D1%86%D0%B5%D0%BD%D1%82%D1%80_%D1%85%D1%80%D0%B0%D0%BD%D0%B5%D0%BD%D0%B8%D1%8F_%D0%B8_%D0%BE%D0%B1%D1%80%D0%B0%D0%B1%D0%BE%D1%82%D0%BA%D0%B8_%D0%B4%D0%B0%D0%BD%D0%BD%D1%8B%D1%85_%D0%9C%D0%BE%D1%81%D0%BA%D0%B2%D1%8B)