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.

DOI : 10.59161/CIPM1993REC1E

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

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