The root of your Model Tree is created by a Child Rule defined on the World node. This Child Rule is written for you by kBridge when you create a new project or when you click right on a Design in the Project Tree and select "Set as Default."
Even though the MyTable this root model was created for you by kBridge when you created a new Project, it is no different from any other model in your project.
Child rules in Designs create a tree of Models, hence the "Model Tree." Models are runtime objects. They have values assigned to their rules as a result of evaluation. This is why you must select the Model context tab to evaluate your rules.