Related Clues:

• Marker
• See 62-Across
• Cash substitute
• Letters of credit
• Debenture, basically
• Grease pencil, for one
• Letters often followed by a number
• Promissory note in a casino
• Chit
• Debtor's note
• Red letters?
• Promise to pay
• Paper in a pot
• Note
• Gambler's I.O.U.