Traceability

Metrological traceability is the property of a measurement result whereby the result can be related to a reference through a documented unbroken chain of calibrations, each contributing to the measurement uncertainty. It is the fundamental concept that guarantees a measurement taken in a local laboratory is mathematically and physically connected to the International System of Units (SI).

Without traceability, a measurement is just a number. With traceability, a measurement becomes a highly reliable estimate of truth, globally comparable and legally defensible. Traceability is what allows advanced manufacturing across different continents to seamlessly integrate parts, and it is what ensures scientific data can be universally validated.

Crucially, traceability is a property of the measurement result, not the instrument itself. It is incorrect to say "this instrument is NIST traceable." Instead, one should say "the measurement results provided by this instrument are traceable to the SI through NIST."