mandatory signs
...that neither the U.S. nor Canada uses UNESCO-defined mandatory signs for traffic?
...that neither the <a href="./United_States" id="mwBsI" rel="mw:WikiLink" title="United States">U.S.</a> nor <a href="./Canada" id="mwBsM" rel="mw:WikiLink" title="Canada">Canada</a> uses <a href="./United_Nations_Economic_and_Social_Council" id="mwBsQ" rel="mw:WikiLink" title="United Nations Economic and Social Council">UNESCO</a>-defined <b id="mwBsU"><a href="./Mandatory_sign" id="mwBsY" rel="mw:WikiLink" title="Mandatory sign">mandatory signs</a></b> <i id="mwBsc">(example pictured)</i> for traffic?