Which clause should you consult when ISO 6789-2 Annex C cites C.5.4 for a certificate?

Check the reference yourself

Find “C.5.4” in Annex C, C.8 e), then work back to the subclauses under C.5. The sequence contains only C.5.1–C.5.3 and proceeds directly to C.6. This is not a case of a subclause appearing on another page or needing to be located in another part: the cited number has no corresponding text in this annex.

Next, identify the results the certificate item asks for: mean values and measurement uncertainty. A questionable cross-reference does not make those results optional. What information the text calls for, and whether its reference leads to the right place, are separate checks.

Why consult the clauses for each result?

C.5.2 addresses the mean value, while C.5.3 addresses the recorded measurement error. C.6 then describes uncertainty sources, and C.7 brings together the calibration result. Following that structure provides a stronger basis than replacing the final digit with any subclause number that happens to exist.

For uncertainty results, distinguish W_md in C.7.2 from W′md in C.7.3. The former is the measurement device’s relative expanded measurement uncertainty; the latter is its relative measurement uncertainty interval. They are not interchangeable names for a single field. If a certificate gives only a percentage, first establish which quantity it represents.

We can therefore confirm that the cited location does not exist and identify where the requested information is addressed. The clause the author originally intended to cite remains a contextual inference. Showing a defensible route through the annex does not formally amend the certificate requirement.

Keep a record that others can review

Record the standard edition, clause, original reference, and adopted reading together. Retain the certificate item’s original location and its printed reference, then note the separate sources used for the mean and uncertainty results. Keep the result symbols, calculation basis, and corresponding calibration points together so that a reviewer can identify what each percentage means.

Base calculations on the clauses that actually address the mean and uncertainty. Do not devise another calculation to fill a nonexistent field. If the issuing organization merely repeats the questionable number, ask it to explain the method used. This article provides a route for checking the reference; it does not establish the completeness of any particular certificate.

This is our reading, not an official ISO corrigendum. ISO is revising Part 1 and Part 2 through committee drafts ISO/CD 6789-1.3 and ISO/CD 6789-2.3. We will update this page and recheck the issue when the revised standards are published.