Article 157 Format of regulatory signals
1. The shape, colour, design, symbols, meaning and dimensions of regulatory signs are those that appear in the official catalogue of traffic signs. The form, symbols and nomenclature are also included in Annex I of this regulation.
2. When the signals referred to in articles 151, 152, 153, 154 and 156 are luminous, it may be assumed that the symbols appear in white on a dark non-luminous background.