Do not sound the horn within the signed restriction, except to warn of danger where local rules allow.
The sign prohibits sounding the horn along the signed stretch or within the signed area. A supplementary plate may show how far the restriction extends.
The common design is a red-bordered circle containing a horn symbol. France’s B16 has a white background and a black horn crossed by a red diagonal bar.
Official sign in each country; the code is its number in the national rules. Signs that come in two directions show the left and the right version.
Sign images from Wikimedia Commons, used under their licences.
