Physical data model of the package structure and the various elements present within the package such as elements, diagrams and sub-packages.
Diagram is the table in which the data about the diagrams is recorded.
Table includes all elements present in the repository. Please note that this determines how an element looks in diagrams and which compartments become visible in the diagrams based on the object_type and stereotype.
Package is actually used for structuring the contents of the repository. It is based on packages and subpackages hence a self reference to the package table via a parent_id