Critical Function of the Project Model
A model is a simplified representation (an abstraction) that defines and communicates a reality or a concept.
The Project Model is the most critical element of the Project and contains all or more of the objects comrpising the Project, such as 
Black Boxes,
Connectors, 
Connections, 
Conductors,
Shields, 
Cables, and 
Passive Components.
Such objects can be added or deleted from the Model as required.
Note that the Properties (definitions or attributes) of each Object are defined in the Properties Panel, when not already defined in the Library.
Related Topics:
Adding and Deleting Objects from the Model
Moving Elements between Model Folders