When is a kilogramme a kilogramme? How do you accurately measure the spectrum of light?
Quantities and units -- Part 7: Light and radiation
A standard is reviewed every 5 years
Revisions / Corrigenda
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Many decisions in life are based on measurements, which need to be sufficiently accurate for the purpose. Making quality-assured measurements is an expertise in its own right, and must be carried out in such a way that everyone can have full confidence in the results.