]A na-ekewa sistemu ụlọ grid ka ọ bụrụ grille main ọgịrịga, ọgịrịga inyeaka na sistemu isi keel nke elu. Ịdị n'otu nke ọgịrịga isi na ọgịrịga inyeaka nke grille na-ezo aka na oghere oghere ígwè. Sistemụ elu ụlọ a na-emepe emepe bụ ihe eji achọ mma mebere site na ngwakọta nke ọgịrịga isi na eriri inyeaka nke grille n'ụzọ kwụ ọtọ na kwụ ọtọ.
