4.3.1. Relationships Summary

4.3.1. Relationships Summary
	4.3. Relationships

[ fromfile: relationships.xml id: relationships-summary ]

You have seen three kinds of relationships:
- Association (purely for navigation)
- Aggregation (containment without management)
- Composition (containment with management)
In addition, each relationship can have the following properties:
- Cardinality – Can be one-to-one, one-to-many, or many-to-many. Often, a number (1, 1..5, *) next to the end of the line segment specifies this.
- Navigability – Can be unidirectional or bidirectional. Unidirectional relationships may have arrows instead of diamonds on the line segments between classes.

Figure 4.3 shows an example using containment and unidirectional relationships.

Figure 4.3. Books and Pages

The diagram indicates that a Book is a (managed) container of Page pointers.
Pages have their own navigation relationships.
The diagram suggests that m_toc (the table of contents) is a linked list of Page pointers.