sec_reference - SECONDARY option

This option marks the relationship as secondary relationship. Only one relationship in a relationship pair can be marked as secondary. Usually, the secondary relationship is the one which is created implicitly in most cases (when adding instances to the primary relationship). It is advised to mark one of the relationships in a bi-directional relationship pair as secondary.

Secondary relationships will not be copied, when using standard copy methods for deep copy, i.e the option does not have strong influence on the behavior of the relationship. The option does not influence the database consistency and can be changed at any time.