The traceability system of measurement standards is indispensable to the improvement of science and industrial development.
The traceability is defined as:"property of a measurement result whereby the result can be related to a stated reference through a documented unbroken chain of calibrations, each contributing to the measurement uncertainty"
Namely, it means that the measurement results in the work field are traceable to the national standards. In November 1st, 1993, the revised Measurement Law was enforced including the traceability system of measurement standards.
Therefore, the JEMIC started the calibration services using the national standards based on the Japan Calibration Service System (hereinafter referred to as "JCSS") in addition to the existing their calibration activities.
The AIST and JEMIC maintain the national standards for the electricity, photometry , thermometry etc.
In the traceability system based on the Measurement Law and supply these measuring standards to the ISO/IEC 17025 accredited calibration laboratories and industries.
The national primary standard is the measuring instrument representing "the quantity of the specified state of physical phenomena" which serves as the standard for measuring instruments and is designated by the Minister of METI.
The national secondary standards are designated as usable standard in place of the national primary standard by the Minister of METI when it is recognized that the national primary standard is unsuitable to use repeatedly calibration of measuring instruments.
Also, the JEMIC plays the role of the JCSS accredited calibration laboratory to disseminate the measuring standards to the industries using the reference standards.
Some of reference standards of accredited calibration laboratories are calibrated by the national primary or secondary standard directly.
Other reference standards are calibrated by the primary standards of accredited calibration laboratories or standards that are traceable to the primary standards.
Japanese traceability system is illustrated below.