Related Clues:

• Sign near a stairway
• "Knock, knock" response
• Tollbooth site
• "Come in" command
• Get off the turnpike
• Escape hatch, e.g.
• [Green]
• Carriage return key, nowadays
• Sign up to compete
• Go in and put in the ledger
• Come in or record
• Come or go in
• Enroll, sign up
• Go or come in
• The way out - go