Recommendation 1 of the 82nd CIPM (1993)

Accuracy of primary frequency standards

The Comité International des Poids et Mesures,


  • that the accuracy of an increasing number of primary frequency standards is now approaching the level of one part in 1014,
  • that new configurations of primary frequency standards have been proposed that appear to have a high potential for accuracy,
  • that at a level of accuracy of one part in 1014 or higher certain corrections must be made that were previously considered insignificant or not sufficiently weIl known,
  • that an essential step in establishing confidence in the accuracy of primary standards is the international comparison of independent standards of different designs,


  • that different configurations of primary frequency standards be made and studied in detail, along with the established ones, and compared using the best means available,
  • that aIl corrections, including those not previously considered significant, be studied in detail and eventually applied,
  • that the results of these comparisons, including full accounts of uncertainties, be communicated to the Bureau International des Poids et Mesures.

reference The reader should note that the official version of this Resolution is the French text

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