[计] mean time between repair, mean time to detection, MTD
píng jūn gù zhàng jiǎn cè shí jiān ㄆㄧㄥˊ ㄐㄩㄣ ㄍㄨˋ ㄓㄤˋ ㄐㄧㄢˇ ㄘㄜˋ ㄕˊ ㄐㄧㄢ