Related Clues:

• Caps Lock, e.g
• Instrumental
• B flat, for one
• One in, or on, a chain
• Pay attention to bank's nominal rate
• A, B or C, for example — short message
• Debt instrument
• What you might pass, but can't fail, in school
• Part of a bird call
• A, B, C, D, F or G, by implication?
• A or G, musically
• A B C D F or G
• Short message; tone
• Give a shout-out to
• Fundamental, and a word that can follow the first parts of 20-, 31-, 41- and 52-Across