Fire protection symbols
The letters "F" or "M" in inverted triangles are fire protection symbols. They indicate the degree of limitation of the heat a luminaire generates and the kind of flammable materials on which the luminaire may be mounted (see table). For all luminaires bearing these symbols, it is imperative that manufacturers' mounting instructions should be observed. The fire protection symbol "D" in an inverted triangle (formerly two "F" triangles) indicates that the heat the luminaire generates is adequately limited for use in industrial and workshop interiors where dust constitutes a fire hazard.
A substance that retards markedly the propagation of a flame. Flame retardants can be incorporated in plastics as additives or as chemical groups in the base polymer by use of reactive intermediates in the polymerisation process.
A relatively inert solid material added to a plastic and evenly mixed with it to improve its strength, stability, processing or other properties or to lower costs.