According to the International Standards Organization (ISO), for companies that are in compliance with ISO-9000 or QS-9000, traceable measurements shall be made when products or processes require dimensional measurements be made to a known uncertainty. These measurements are often made with a traceable ruler or micrometer. For magnification (the ratio of object size to image size) to be traceable, both the image and object size must be measured with calibration standards that have traceable dimensions. In the current ISO jargon the “uncertainty” of the instruments used to make the measurements must be known. The word “accuracy” is now only considered to be a subjective term and shall remain dimensionless.