- geolocation - if you want to know where I am, before I decide to approve the request I want to know where you currently are. Maybe I won't share mine if you are within a certain minimum distance.
- home address - similar to above but perhaps I'll only release my address if you live in the same city
- marital status - 'nuff said
To duplicate this in the digital world would require a number of pieces (not necessarily all):
- the ability to express this preference as an access control policy.
- the ability for this preference to be advertised to potential requestors, or the ability for non-compliant requests to be failed with appropriate fault information.
- the ability for a request for some piece of identity to include any of
- the same piece of identity for the requestor.
- the location of the same piece of data for the requestor.
- how to discover the same piece of data for the requestor.