Site Restriction and Addresses for the contact fields in Contact Directory of Supplier setup

We are on 12.2.3 and have some contacts in the supplier setup that have a address specified for them example site MAC-1 under the region addresses for the contact and under site restriction region we have this contact haviing sites MAC-1, MAC-2 and so on.How do these two regions site restriction and addresses for the contact work?we know if we enter a value under site restriction , then this contact gets POs only for having that site on them and no other.However if the contact also has a value specified under the addresses for the contact field how does that