The VIM's fourth edition: what's changing in metrology's vocabulary

The International Vocabulary of Metrology — the VIM — is the document that decides what words like calibration, traceability and uncertainty actually mean. The current third edition (JCGM 200:2012) has anchored those definitions for over a decade, and every entry in this Atlas dictionary cites it.

A fourth edition has been in development within the JCGM's working group for years, with a committee draft circulated to national metrology institutes and liaison organizations for comment. Among the themes the revision has wrestled with: a fuller treatment of nominal properties and examinations (qualitative 'measurements' such as blood typing or material identification), how deeply the uncertainty-centred view of measurement should shape the core definitions, and clearer language around measurement models.

What should a working laboratory do about it? Nothing drastic. Vocabulary editions change slowly, procedures cite the edition they were written against, and VIM3 remains the version of record until the JCGM publishes its successor. The practical habit worth keeping: cite the VIM edition and clause when a definition matters — as the entries in this dictionary do — so a future edition change is an update, not an archaeology project.