Relationships can exist from a Class to itself and represent a hierarchy. These are known as self or recursive relationships. They are also described as a “Pigs Ear” by the way they are represented on a diagram. A simple example is that a Manager may be a Manger and also be managed by a Manager.
This association between the higher level class and its lower level subdivisions is indicated by a square line in the top right hand corner of the class.
An example of a Recursive Relationship in diagrams is given below: