After refactoring the dates we decided to drop the table model.link_property because the only entries left there are type links.
These links are used to give types to links (e.g. has relationship, had participant). Because in these cases (they are system types) only one type can selected we will move this information into the model.link table with a new field called "type_id" which will have a foreign key constraint to the model.entity id field.
There will be no noticeable changes in the user interface but the database structure will get simpler and easier to process.