An example of a final class definition for the Industrial sector, derived by a self-organizing map of 1000 nodes (classes), using an emission matrix where Tracer C and Tracer I are the only tracers expected to be emitting, as highlighted by the light blue box over the Industrial sector’s row. Here “Scaled” means that the tracers should have enhancements with magnitudes linearly scaled with CO₂ff (in this case, the scale factor = 1, so they should have identical values). In this example, four of the noise species in the dataset have higher mean enhancements than the known emitting tracers, which may be problematic in a real-world case where it was not known ahead of time which tracers are expected to be emitting. DOI: https://doi.org/10.1525/elementa.131.f5