The fourth educational module on the International Treaty focuses on the Multilateral System functions provides an overview of the legal and historical perspectives that lead to the development of the Multilateral System and the list of Annex I crops. It also illustrates the core concepts and articles of Section IV of the International Treaty. The first two lessons are aimed at a broad target learner group, especially at learners that are new to the Multilateral System. Lessons three and four contain practical elements related to the day-to-day operations and may be of interest to those exchanging material and involved in the planning and implementation of the Multilateral System at the national level. All lessons provide an extensive list of resources and references for further reading and learning. It has been designed to contribute to supporting the implementation of the International Treaty and also the Post-2020 Global Biodiversity Framework.