Resolution 9 of the 24th CGPM (2011)

On the adoption of a common terrestrial reference system

The General Conference on Weights and Measures (CGPM), at its 24th meeting,


  • that a significant number of global navigation satellite systems (GNSS) now exist and that in the future there may be more,
  • the proliferation of time and geodesy reference systems in use in these navigation systems, which creates ambiguities for users with regard to the interpretation of navigation and timing solutions, and which renders interoperability between the systems more difficult,
  • the existence of the International Terrestrial Reference System (ITRS),
  • that the adoption of a common reference system would lead to benefits for users regarding unification of navigation and timing solutions and systems interoperability,

recommends that the ITRS, as defined by the International Union of Geodesy and Geophysics (IUGG) and realized by the International Earth Rotation and Reference Systems Service (IERS), be adopted as the unique international reference system for terrestrial reference frames for all metrological applications.

DOI : 10.59161/CGPM2011RES9E

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

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