The organizational structure of the CIPM MRA is indicated in Figure 1 and the scheme for key comparisons is shown in Figure 2. Each of these figures is for illustrative purpose only; the text of the MRA and the Guidelines for CIPM Key Comparisons should be consulted for full details. Printed copies of the MRA and the Guidelines can be obtained from the BIPM.

The regional metrology organizations (RMOs) play an important role in the MRA. They have responsibility for carrying out key comparisons within their regions, they carry out supplementary comparisons and other actions to support mutual confidence in the validity of calibration and measurement certificates of their member NMIs and are responsible for coordinating, through the JCRB, the entries into Appendix C of the MRA of the calibration and measurement capabilities of their member NMIs.

Figure 1. An outline of the organization of the MRA.

Figure 2. The scheme for key comparisons.

	National metrology institute (NMI) participating in CIPM key comparisons
	NMI participating in CIPM key comparisons and in regional metrology organization (RMO) key comparisons
	NMI participating in RMO key comparisons
	NMI participating in ongoing BIPM key comparisons
	NMI participating in a bilateral key comparison
	International organization signatory to the MRA