Establishes a classification of tower cranes as defined in ISO 4306-3, according to their category (1: in irregular use or having a light state of loading, 2: for building, 3: in regular use or having a heavy state of loading). Applies to the classification of tower cranes for building and general construction work that can be dismantled, permanently erected tower cranes, hammerhead cranes, dockside and shipbuilders' tower cranes. Does not apply to the classification of power-driven mobile jib cranes which may be fitted with a tower attachment and erection masts, with or without jibs.