File:Belgian traffic sign C21 maxweight uitgezonderd laden lossen, vergunning en bus autocar.png

This image is a Belgian road sign and is public domain since it is part of the legislation of Belgium (article 8, § 2 of the Copyright Act).
Note that it is proper license for traffic signs diagrams, photos carry also copyright of a photographer (unless expired).

This image or logo only consists of typefaces, individual words, slogans, or simple geometric shapes. These are not eligible for copyright alone because they are not original enough, and thus the image is considered to be in the public domain.
See  Public domain or Restricted materials on Wikipedia for more information.
Please note: The public domain status of this work is only in regards to its copyright status. There may be other intellectual property restrictions protecting this image, such as trademarks or design patents if it is a logo.