The GUM will probably not change. The JCGM (Joint Committee for Guide in Metrology WG1) is organising the publication of a series of documents relating to and supporting the GUM. The following documents have already been published. NF ENV 13005:2009 - Guide to the expression of uncertainty in measurement (reproduces the ISO Guide 98:1995). FD ISO guide 98/S1 Evaluation of measurement data - Supplement 1 of the Guide to the expression of uncertainty in measurement - Propagation of distributions using aMonte Carlomethod.