A UML model can completely describe a variety of systems using both syntactic element definition and semantic diagram rendering. Although semantics are not included in the UML specification, they are important to a UML model in that they clarify meaning and enhance understanding for human readers. It is also possible to enhance diagrams with non-UML elements such as shapes and text objects. These items will not appear in any generated code, but they will be available for viewing within the diagrams.
Several views of the elements are available within Poseidon. These are available from the tabs in the Navigation pane, and include:
Each of these present the elements in a tree view with a different focus in mind. But one thing they all have in common is the root node, which is the model itself. In every UML model, it is the top level namespace.