ISO/IEC Guide 98-3:2008/Suppl.2:2011 is concerned with measurement models having any number of input quantities and any number of output quantities. The quantities involved might be real or complex. Two approaches are considered for treating such models. The first approach is a generalization of the GUM uncertainty framework. The second is a Monte Carlo method as an implementation of the propagation of distributions. Appropriate use of the Monte Carol method would be expected to provide valid results when the applicability of the GUM uncertainty framework is questionable.

For a prescribed coverage probability, ISO/IEC Guide 98-3:2008/Suppl.2:2011 can be used to provide a coverage region for the output quantities of a multivariate model, the counterpart of a coverage interval for a single scalar output quantiy. The provision of coverage regions includes those taking the form of a hyper-ellipsoid or a hyper-rectangle. These coverage regions are produced from the results of the two approaches described here. A procedure for providing an approximation to the smallest coverage region, obtained from results provided by the Monte Carol method, is also given. Detailed examples to illustrate the guidance are provided.