Because diffusive mass flux links can be bi-directional, it is important to understand the sign convention used by GoldSim when displaying and using the diffusive mass flux outputs.
Although a diffusive mass flux link can be bi-directional (i.e., mass fluxes can move in either direction along the link), GoldSim always defines one of the two pathways as the "Outflux Pathway" and one of the pathways as the "Influx Pathway". The pathway from which the link was created via the Diffusive Fluxes tab is identified as the Outflux Pathway for the link.
Diffusive mass fluxes away from the Outflux Pathway in the link are, by convention, positive, and diffusive mass fluxes toward the Outflux Pathway are negative.
Within the Diffusive Fluxes tab for Cell pathways, links in which the cell is the Outflux Pathway are always listed first. Note that because you cannot create a diffusive mass flux link from a non-Cell pathway, non-Cell pathways involved in a diffusive mass flux link can never be an Outflux Pathway.