– the intergovernmental organization through which Member States act together
     on matters related to measurement science and measurement standards.
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CCL Working Group on the CIPM MRA (CCL-WG-MRA)

At its meeting in September 2012 the CCL approved the following terms of reference for the CCL-WG-MRA:

  1. Tasks
    • To maintain links with the regional metrology organizations, seeking to ensure the involvement of member laboratories of the CCL in major comparisons in the field of length, thereby providing the means for assuring world-wide traceability and equivalence of length measurements at the highest levels of accuracy;
    • To make recommendations to the CCL on the needs and priorities for additional international comparisons in length under the auspices of the CCL;
    • To ensure the coordination of CCL and RMO key and supplementary comparisons;
    • To approve the Length key comparison protocols and reports;
    • To facilitate the inter-regional CMC Review Process, by:
      1. establishing and maintaining lists of service categories, and where necessary rules for the preparation of CMC entries;
      2. agreeing on detailed technical review criteria;
      3. coordinating and where possible conducting inter-regional reviews of CMCs submitted by RMOs for posting in Appendix C of the CIPM MRA;
      4. providing guidance on the range of CMCs supported by particular key and supplementary comparisons;
      5. identifying areas where additional key and supplementary comparisons are needed;
      6. monitoring the review of existing CMCs in the context of new results of key and supplementary comparisons;
    • To report to the CCL.

  2. Organization
  3. The WG-MRA has the following sub groups and task group:

  4. Membership
    • The WG-MRA Chair is appointed by the CCL for a period of 4 years (renewable);
    • Membership includes members of the sub working groups and task groups, and the moderators of the discussion groups;
    • Full voting Members are nominated by the CCL, and non-voting members may be invited by the WG-MRA, through the Chair.


  • Dr Andrew Lewis  (NPL)


  • ex officio members: TG chairs, members of TGs

Sub-Working Groups and Task Group:

Discussion Groups:

  • DG1
  • Gauge blocks A. Lewis, NPL
  • DG2
  • Thermal expansion T. Takatsuji, NMIJ/AIST
  • DG3
  • Angle O. Kruger, NMISA
  • DG4
  • Cylindrical diameter standards J. Stone, NIST
  • DG5
  • Step gauges E. Prieto, CEM
  • DG6
  • Coordinate metrology E. Prieto, CEM
  • DG7
  • Linescales H. Bosse, PTB
  • DG8
  • Surface texture A. Baker, NMIA
  • DG11
  • Mise en pratique lasers and fs combs M. Matus, BEV

  CCL: Upcoming meetings
11–15 June 2018: 17th meeting of the CCL and related meetings

CCL summary
General information
Members of the CCL
CCL key comparison portfolio
DimVIM: Multilingual CMC classification scheme
CCL publications and bibliography
CCL working groups
Key comparisons
Photographs of the CCL
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WGFS documents
CCL-WG documents