Linking resources with "Use the primary keys to make the join"
Hello,
I´m diving in custom resource´s creation, specially in defining links. I have always used "Define specific keys to make the join" when defining joins: i select one field from every resource involved in the link and thats how resources are joined.
I see that there is also another option available: "Use the primary keys to make the join".

I would like to undertand how could i use this option to join resources. If i set this option, which field does ACS use from the source resource to link to the target resource ?(i guess that it uses target resource´s primary key)
Thanks and best regards!
Mario