Related Clues:

• Take heed
• Quick message
• Chirp
• Refrigerator attachment, maybe
• Bulletin board notice, perhaps
• Staff marking
• IOU, e.g.
• Middle C, e.g.
• Headache for Dilbert
• '___ to self . . .'
• Staff member
• Symbol on a staff
• Jot down
• Canary cry
• Musical staff symbol