ISO Glossary of Terms

person who provides specific knowledge or expertise to the audit team

Note 1 to entry: Specific knowledge or expertise relates to the organization, the activity, process, product, service, discipline to be audited, or language or culture.

Note 2 to entry: A technical expert to the audit team (3.14) does not act as an auditor

Traceability is the property of the result of a measurement or the value of a standard.  It can be related to stated references, usually national or international standards, through a consistent chain of comparisons with stated uncertainties