What does a red circle with a slash on a white background indicate?

• The action shown inside the circle is allowed.
• The action shown inside the circle is prohibited.
  Explanation:

  "A red circle with a slash on a white background is a universal symbol for prohibition. It indicates that the action or activity depicted inside the circle is not allowed or prohibited in that area."
• The road is closed to all traffic.
• The speed limit in the area is enforced.