Description: mathematical expectation of the operating time between failures; Name: mtbf
Description: expectation of the operating time between failures; Name: mean time between failures (MTBF)
Description: norm/stipulation describing the explosion protection. The explosion protection type, the device category, the temperature class as well as the device / explosion group are taken from this norm. The type and number of the norm/stipulation with issue year and issue month must be given; Name: Reference norm of the explosion protection