This read-only TimeTicks value reports how long this specific stack unit has been running, in hundredths of a second. In a stack, an admin uses this per-unit uptime, rather than a single stack-wide uptime, to spot a unit that rebooted independently of the others, which can indicate a localized hardware or power problem. For example, if unit 3 shows a much lower uptime than the other stack members, the admin knows that unit rebooted recently on its own and should check its logs for the cause.