The introduction pathway classification framework developed for the Convention on Biological Diversity and changes, shown in bold, to the framework as recommended in guidelines produced by Harrower et al. (2018). The guidelines were written specifically to avoid making major changes to the framework. The proposed structural changes were that two overlapping sub-categories be merged and that a catch-all sub-category (called ‘other contaminant’) be added for contaminant introductions that do not fit into any of the detailed sub-categories.