Mfundo yogwirira ntchito:Zida zimakhudzidwa ndi kugwedezeka kwakukulu kwafupipafupi m'chipinda champhero. Mphamvu zowononga zimaperekedwa kudzera mu milling matrix (mpira, ndodo, forge, ndi zina), ndipo zida zimapukutidwa ndi mikangano, kugundana, kumeta ubweya ndi mphamvu zina.