Three basic methods are described in this standard for calibrating laterally-modulated frequency records. The same general techniques also are applicable to vertically-modulated frequency records. The oldest of these is the Microscope Method, in which the recorded amplitude is measured directly by use of a microscope. The second method is the Light-Pattern Method, in which the recorded amplitude is determined by use of the principle that, under specified conditions, the reflected light from a band of recorded grooves forms a pattern the width of which is related to the recorded velocity. The main body of the Standard covers the Light-Pattern Method due to Buchmann-Meyer, while in the Appendix are given two approved refinements for improving accuracy of observation, particularly at short-recorded wavelengths.