<p>I give a short personal view on what are National Measurements Institutes. More info can be found here:</p>
<ul>
<li><p><a href="https://en.wikipedia.org/wiki/Measurement_uncertainty" class="uri">https://en.wikipedia.org/wiki/Measurement_uncertainty</a></p></li>
<li><p><a href="https://en.wikipedia.org/wiki/Metrology" class="uri">https://en.wikipedia.org/wiki/Metrology</a></p></li>
<li><p><a href="https://en.wikipedia.org/wiki/International_Bureau_of_Weights_and_Measures" class="uri">https://en.wikipedia.org/wiki/International_Bureau_of_Weights_and_Measures</a></p></li>
<li><p><a href="https://en.wikipedia.org/wiki/National_Physical_Laboratory_%28United_Kingdom%29">https://en.wikipedia.org/wiki/National_Physical_Laboratory_%28United_Kingdom%29</a></p></li>
<li><p><a href="https://en.wikipedia.org/wiki/Physikalisch-Technische_Bundesanstalt" class="uri">https://en.wikipedia.org/wiki/Physikalisch-Technische_Bundesanstalt</a></p></li>
<li><p><a href="https://en.wikipedia.org/wiki/National_Institute_of_Standards_and_Technology" class="uri">https://en.wikipedia.org/wiki/National_Institute_of_Standards_and_Technology</a></p></li>
</ul>
<p>One thing not mentioned but related is ISO:</p>
<p><a href="https://en.wikipedia.org/wiki/International_Organization_for_Standardization" class="uri">https://en.wikipedia.org/wiki/International_Organization_for_Standardization</a></p>