Follow the measurement back
NIST’s traceability FAQ describes a measurement result connected to a reference through a documented calibration chain, with uncertainty at each step. An instrument calibrated by NIST does not automatically make every later result traceable. Buying a reference material is also only one part of the evidence.
Apply that idea to concentration
For a result expressed as mass per volume, S7 suggests asking how the mass and volume values were established and how those inputs support the final result. A printed unit tells the reader what kind of quantity is reported; it does not provide the measurement history. Likewise, a certificate heading cannot replace the supporting records.
Traceable still needs to be suitable
NIST distinguishes traceability from fitness for a particular purpose: the uncertainty may still be too large for the intended decision. Our reading checklist is therefore: identify the quantity, identify its reference, follow the documented comparisons, then consider the required confidence. This explains measurement records, not mixture preparation. The illustrated chain is a metaphor, not a calibration procedure.