When a custom record has a field in which the checkbox Applying Role-Based Restrictions is checked and suppose the field type as subsidiary list/record. A user with specific subsidiary access role can only view those subsidiary based custom records which are of the same subsidiary as that of the user.
You can apply the restrictions set on role records for a particular category (department, class, location, employee, or subsidiary) to a custom record, by checking the Apply Role Restrictions box for a list/record custom field that stores values in one of these categories. For example, if you check this box for an Employee list/record custom field, the employee-based restriction set on the Sales Manager role record is applied to this custom record. Those users see only custom records where they or their subordinates are the value for the custom field.
When a custom record has a field that permits restrictions, and the Apply Role Restrictions box is checked, empty fields are not included when the restrictions are applied. When role restrictions are enabled for a custom record, there is no way to view or edit a record where the role-related field is empty. For example, if your user role is restricted to Subsidiary A, and a custom record is created that does not specify a subsidiary, your view is restricted to Subsidiary A. You will see only records where Subsidiary A is selected, and you will not see any records with empty subsidiary fields.