This read-only TimeTicks reports the time, in hundredths of a second, since the bridge last detected a Spanning Tree topology change. An admin cares because frequent topology changes indicate an unstable link or flapping port, which causes repeated network disruption as STP recalculates. For example, an admin noticing intermittent connectivity issues would poll this counter over time and, seeing it reset frequently, conclude that a flapping link is repeatedly triggering STP recalculation.