Towards a new GUM—an update

The contents of the current edition, JCGM 100:2008, of the Guide to the Expression of Uncertainty in Measurement (GUM) and its Supplements are reviewed and remarks made concerning a proposed revision of the GUM. A committee draft of the revision was circulated to member organizations of the Joint Committee for Guides in Metrology (JCGM) and all national metrology institutes in December 2014. The motivation for the proposed changes is given and reactions to the committee draft are summarized. Some of the contents of this paper are solely an expression by the authors and do not constitute an official statement by the JCGM.