The relationship between entities can be declared using the following syntax:
relationship <type> { <from entity>[{<relationship name>[(<display field>)] <validation>*}] to <to entity>[{<relationship name>[(<display field>)] <validation>*}]}
The <type> can be OneToMany, ManyToOne, OneToOne, or ManyToMany, and as the name suggests, declares the relationship type between <from entity> and <to entity>.
The <from entity> phrase is the name of the owner entity of the relationship or the source. The <to entity> phrase is the destination of the relationship.
The <relationship name> phrase is optional and can be used to specify the field names to be created for the relationship in the domain object. The <display field>
