Organizations
The latest train of thought in AIRport development is enabling discrete data sharing between Organizations. Organizations could range in type from a family to a governmental agency.
Each Organization would set up a set of access levels for its Repositories. It would also give its member Users corresponding access levels, thus limiting which Users can access which Repositories. Large Organizations with multiple sub-organizations would work the same way - the Repositories of sub-organizations would inherit the parent organizational hierarchy with the option of overriding it with its own access level and access level assignments. The overridden values would only apply to the sub-organization that made the overrides.
Across unrelated (sub-)Organizations, a set of mappings will allow association access levels of a foreign Organization to own access levels. This allows for discrete data sharing between Organizations (for data that could benefit them collectively).
Permission access level will also be modifiable per Repository level, allowing an Organization to elevate or relax access to certain Repositories it owns. It will also be possible to allow specific Users access to Repositories that would otherwise have access levels above their clearance (based on organizational or cross-organizational rules).
Since Repositories are interdependent they can reference other Repositories. With organizational checks in place, Repositories will reference only Repositories with equivalent or lower access levels (or their cross-organizational equivalents).