Related Clues:

• Express letters?
• Abbr. on an order
• Bus. envelope notation
• ''... and make it fast!''
• 'Stat' in memos
• 'Yesterday!'
• Order request
• 'Quick!'
• Env. abbreviation
• Pronto!
• "On the double!"
• Order heading
• Initials for the impatient
• Promptness prompter
• Memo heading