Where does this come from, and can I check it?

ISO 3864 reserves the slashed circle for conduct that is not allowed. The figure is taken from International Organization for Standardization, which is linked in full on this page. Every fact on Mondo Knows names its source rather than repeating an unsourced claim.

Is this really a everyday life fact?

Yes. It sits on the Everyday Life shelf, one of 2,600 sourced facts grouped into space, animals, the human body, history, science and more. Category pages collect every fact in the same field.

What else can I read about it?

The links under the fact point to a quiz, game, puzzle or calculator on the same subject, and the shelf below shows related facts. The wording here is original, and quoted phrases are marked as quotations.

Mondo Knows Facts

Red circle signs forbid an action outright

ISO 3864 reserves the slashed circle for conduct that is not allowed Safety signs follow a colour code set out in ISO 3864: a red circle with a diagonal bar forbids an action, a blue circle requires one, and a yellow triangle warns of a hazard. The shapes differ as well as the colours, so the message survives red-green colour blindness. Fire equipment is marked red while escape routes are green. It sits in Mondo's everyday life collection, one of 200 facts that each trace back to the reference below.

Where this comes from

International Organization for Standardization

Facts that can change over time are reviewed and updated. If something here looks wrong, Mondo would rather know than be confidently incorrect.

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Tags: signage, standards, safety

Red circle signs forbid an action outright: the short answers

Where does this come from, and can I check it?: ISO 3864 reserves the slashed circle for conduct that is not allowed. The figure is taken from International Organization for Standardization, which is linked in full on this page. Every fact on Mondo Knows names its source rather than repeating an unsourced claim.
Is this really a everyday life fact?: Yes. It sits on the Everyday Life shelf, one of 2,600 sourced facts grouped into space, animals, the human body, history, science and more. Category pages collect every fact in the same field.
What else can I read about it?: The links under the fact point to a quiz, game, puzzle or calculator on the same subject, and the shelf below shows related facts. The wording here is original, and quoted phrases are marked as quotations.