If you have a model which has modellink to Organization model then you can apply Partnership permissions. This means the user can read or write this model if the user's org has a mutual partnership with the selected organization field. ("Mutual partnership" means my org has a partner record pointing to yours, and your org has a partner record pointing to mine.)
Within Partnership permission, different entities are OR'd when determining access, similar to dimension and related model permission.
In the above example, we have provided read permission to ZBKS.SampleRoleType based on ValueChain dimension permission and Partnership permission to Supplier field (which is an Organization ModelLink field on Book).