What does a red circle and diagonal slash on a sign mean?

Related questions

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4. What is a zero with a slash through it mean?
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7. Do you put a line through O or 0?
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Tags

1. #indicate
2. #right
3. #pictogram
4. #completely
5. #known
6. #official
7. #circle
8. #enclosing
9. #symbol
10. #backslash
11. #something
12. #bottom
13. #prohibition
14. #general
15. #universal
16. #diagonal
17. #through
18. #according
19. #interdictory
20. #running