Related Clues:
- Timetable letters
- 'Check back later' letters
- Placeholder letters
- Letters in an incomplete schedule
- Mandated: Abbr
- Letters in an unfilled sched. slot
- Not scheduled yet: Abbr
- Undecided, on a sched
- 'We'll let you know later': Abbr
- Not yet decided (Abbr.)
- 'Don't know yet,' on skeds
- "Don't know yet," on skeds
- Alternative to '?,' in some listings
- Place-holding abbr
- 'When we know, you'll know': Abbr