This object reports the timestamp of the previous configuration file that was automatically backed up during a configUse action, expressed as seconds since midnight January 1, 1970. A value of zero tells an admin no backup copy exists yet, while a nonzero value lets them confirm exactly when the last safety copy was made before deciding whether it's safe to roll forward with configBack. For instance, if this object reads a timestamp corresponding to six months ago, an admin would know the equipment hasn't had a config change applied via configUse since then.