Layout of the diagram model with the Eclipse Layout Kernel: diagrams to ELK graphs, layout options from element properties, and the results written back into bounds, ports, waypoints and labels. Its Nasdanika Zephyr Book, "Diagram Layout with ELK", is built from src/docs/asciidoc with listings from the tests, which generate diagrams of Ecore packages and render them with React Flow and Draw.io.