This interface describes an object that knows how to format or otherwise render an object appropriately. Usually this is used for locale changes for objects such as Date and floating point numbers... You can either have an object that is sensitive to the locale or have a different object per locale. Each template may have a renderer for each object type or can default to the group's renderer or the super group's renderer if the group doesn't have one. The toString(Object,String) method is used when the user uses the format option: $o; format="f"$. It checks the formatName and applies the appropriate formatting. If the format string passed to the renderer is not recognized then simply call toString(). @since 3.1