Nexus is a Scaling Network based on Scrum used for 3 to 9 Scrum Teams. A Nexus structure is headed by a Nexus Integration Team (NIT), which coordinates the other Scrum Teams. The NIT consists of the Product Owner, a Scrum Master and a Development Team. The other Teams have no Product Owner and Scrum Masters are optional. Nexus knows an additional Event, the Nexus Sprint Planning where Product Backlog Items are assigned to the different Teams. Refinement events are taking place first in the NIT, then in the individual Teams, then again in the NIT.