Related Clues:

• Concern of some codes
• CTRL, e.g.
• Integral
• "Defense of Fort M'Henry" writer
• G, but not H
• Kind of code at some schools
• Decoder's tool
• Rebuke (with "down")
• C minor, for one
• Formal
• Answer sheet
• A flat, e.g.
• Suit yourself?
• Boutique buy, perhaps
• Sardine-can opener