[经] economic standard order quantity
biāo zhǔn jīng jì dìng huò liàng ㄅㄧㄠ ㄓㄨㄣˇ ㄐㄧㄥ ㄐㄧˋ ㄉㄧㄥˋ ㄏㄨㄛˋ ㄌㄧㄤˋ