Data scope setting for relationship fields is similar to data scope setting for blocks, setting default filter conditions for relationship data.

Example: Only on-sale products can be selected for association.

Example: Only products with production date earlier than last month can be selected for association.

For more about variables, refer to Variables
Relationship fields achieve linkage through setting data scope.
Example: The order table has many-to-many relationship field "Products" and many-to-one relationship field "Customer". The products table has many-to-many relationship field "Customers". In the order form block, the selectable data for products is products associated with the customer selected in the current form.
