Related Clues:

• Up in the air, for short
• Unknown time letters
• Not yet filled, in a sched.
• Not optional: Abbr
• Basic, in coll
• Awaiting scheduling: Abbr
• 'Details forthcoming': Abbr
• TV schedule abbr
• Like core courses: Abbr
• Not opt
• Like some univ. courses
• "I'll tell you later," TV Guide-style
• Mandatory coll. course
• Mandatory: Abbr
• Sched. slot notation