Given the other example on this thread, it appears that the first time zone assigned to a floating time is adopted as the time's TZ. Assign the TZ for the floating time value to wherever that value was generated. For all we know, the timezone for that string could be the Aleutian Islands, Anchorage, Alaska, Tokyo, London, or Timbuktu. Until there is something to anchor it to, you cannot do a comparison that has any meaning.