About Foreign Key Relationship

In the Relationship Definition section, you can also create a relationship between two families by using a Foreign Key relationship. All the relationship definitions for a foreign key relationship family will be in a Foreign Key relationship. Creating a Foreign Key relationship improves the performance of data retrieval.

Each Foreign Key relationship consist of the following elements

A relationship family
A predecessor entity family
A successor entity family
Cardinality

When using a Foreign Key relationship, you should consider the following:

All the relationship definitions for a Foreign Key relationship will have the same cardinality.
The Many To Many cardinality is not supported for a Foreign Key relationship.
The cardinality of a Foreign Key relationship cannot be modified.
The Foreign Key relationship does not contain fields, rules, or policies.