Related Clues:

• Letter abbr.
• Letters on letters
• Abbr. on 14-Across
• Abbr. on a business letter
• Memo header
• Abbr. at the top of a memo
• Abbr. on an order
• Bus. envelope notation
• Env. abbreviation
• Memo heading
• Memo directive
• E-mail subject line abbr.
• Abbr. that may precede a colon
• FYI equivalent
• Env. notice