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: A suitable, minimum (usually rounded) value of a frequency which is used for the description, designation or identification of a part, device, operating resource, facility or set of equipment; Name: Min. nominal frequency