Tolerance checking marker system for data cards - has series of fine lines for visual or machine read-out printed in coloured magnetic inks

摘要

The tolerance checking system for coded data cards and other information storage and retrieval devices consists of a series of double parallel lines placed at strategic points on the surface of the card. The method allows a check to be made for accuracy at the corners, for exact spacing of a line raster from the edge (4)(2) and along the entire length of the card and for the correct positioning of a magnetic strip (3)(5) with respect to the edge of the card. If the narrow tolerance markers (4) are printed with coloured magnetic inks, both vasual-with magnifying optics - and machine reading methods can be