Guide to the Expression of Uncertainty in Measurement: establishes general rules for evaluating and expressing uncertainty in measurement that are intended to be applicable to a broad spectrum of measurements. The basis of the Guide is Recommendation 1 (CI‑1981) of the Comité International des Poids et Mesures (CIPM) and Recommendation INC‑1 (1980) of the Working Group on the Statement of Uncertainties. The Working Group was convened by the Bureau International des Poids et Mesures (BIPM) in response to a request of the CIPM. The ClPM Recommendation is the only recommendation concerning the expression of uncertainty in measurement adopted by an intergovernmental organization. https://www.iso.org/sites/JCGM/GUM-JCGM100.htm