Is a schema, diagram, or other visual representation available that identifies relationships within and between the four layers (business, application, etc.)? This would make it so much easier to understand relationships and potential impact of changes.

Neil, please update the link to the blog article to remove the date. It should be:
https://www.enterprise-architecture.org ... essential/

BTW, it worked for me, as well. Thanks!

How should EA_System be used?

A security vulnerability exists with Graphviz. Can another product be used in its place?