Description: Period of time during which an item performs its intended function, it includes all the time a machine is continuously running from start-up until it is shut down.; Name: ot
Description: passed time period after comissioning of a system, sub-system, component or piping; Name: Operating time 
Description: ten times the logarithm to the base 10 of the ratio of the sound power of a source, p, to a reference value, p0, expressed in decibels; Name: sound output level