This European Standard specifies the heat soak process system together with tolerances flatness, edgework, fragmentation and physical and mechanical characteristics of monolithic flat heat soaked thermally toughened soda lime silicate safety glass for use in buildings. Information on curved heat soak thermally toughened soda lime silicate safety glass is given in Annex B, but this product does not form part of this European Standard. Other requirements, not specified in this European Standard, can apply to heat soaked thermally toughened soda lime silicate safety glass which is incorporated into assemblies, e. g. laminated glass or insulating units, or undergo an additional treatment, e. g. coating. The additional requirements are specified in the appropriate product standard. Heat soak thermally toughened soda lime silicate safety glass, in this case, does not lose its mechanical or thermal characteristics.