1. The hazard warning sign to be affixed to a freight container or receptacle shall be that shown in column 3 of Part 1 of this Schedule for the classification of the explosives shown in the corresponding entry in column 2 of that Part, and the signs shall conform in form to those shown in the said column 3, except that the sign may show the class number in accordance with the IMDG Code and in the case of classes 1 and 7 must show the Class number. The background colour of the signs shall be orange, pictographs, numbers, letters and lines shall be black.
2. Each hazard warning sign shall be in the form of a square set with its sides at an angle of 45° to the vertical and the length of the sides shall be not less than 100 millimetres, except that, in the case of receptacles that are of such dimensions that they can only bear smaller signs, the sign should be as large as is reasonably practicable.
3. Hazard warning signs to be affixed to a freight container or receptacle shall have a line of the same colour as the symbol, 5 millimetres inside the edge and running parallel to it. (The broken line which surrounds each sign delineates the edge of that sign and need not be shown.)