This International Standard specifies the method for determining the ISO speed and ISO range of black-and-white photographic papers used to make positive reflection prints of continuous-tone subjects from black-and-white film negatives. It pertains to all conventional silver-halide contact and enlarging papers used for continuous-tone or pictorial photography. This includes papers with variable contrast. The papers may be processed in conventional chemicals and equipment, but also using special procedures such as those involving activators or heat for development. This International Standard does not apply to: non-silver papers; high contrast silver papers, such as those used in the graphic arts, or other non-pictorial applications; silver papers used to obtain a direct positive or reversal image.