Pronounced wu geng (falling tone) in the "Guangyun" and mei geng (falling tone) in the "Jiyun," with the same pronunciation as "mang" (flat tone). It means to melt or destroy. Also, according to "Zhengzitong," it refers to the current flying spear. "Dongguan Hanji" records: Emperor Guangwu created a flying spear (feibeng), used to attack the Red Eyebrows army. The character "beng" should be written as "lei."