Lays down detailed specifications for the instrumentation and procedure to be used for primary calibration of accelerometers at low frequencies. Applies to all kinds of pick-ups. Is applicable for a frequency range from 0,5 Hz to 20 Hz and a dynamic range from 1 m/s^2 to 200 m/s^2 (frequency-dependent) and from 0,5 mm to 1000 mm. The limits of uncertainty applicable are 0,5 % of reading.