SCTE 104/35 Codex

How much time is left in the event, counted in 100-microsecond units, so 10,000 units is one second. For an event with a known duration it equals the full duration at the start and decrements toward zero as the event runs. When the duration is indeterminate or open-ended, remain instead carries the all-ones sentinel 0xFFFFFFFFFF, which is not a real remaining time.