Diagramming Conventions
 

Relationship Cardinality

Cardinality is indicated by the presence of numbers on either end of the relationship line connecting class types.

0..* indicates that the cardinality is may be related to one or more instance of the class
0..1 indicates that the cardinality is may be related to one and only one instance of the class
1..* indicates that the cardinality is must be related to one or more instance of the class
1 indicates that the cardinality is must be related to one and only one instance of the class

An example of relationship cardinality in diagrams is given below:

UML Diagramming Convention showing the Class of PATIENT and the Class of HOSPITAL PROVIDER SPELL and the Relationship that exists between these two classes. A HOSPITAL PROVIDER SPELL