Registries of persons and organizations are necessary as a resource to uniquely identify individuals, projects, organizations, and other kinds of entities in a federated system, with open world semantics and non-unique naming of resources.

Some registries required for interoperable distributed information system:

Service Types. The ISO19119 service metadata content model requires a 'ServiceType' property to categorize a service, but there seems to be no widely used registry that can provide and authoritative list of service types along with an identifier for the service type.The Canadian Geospatial Data Infrastructure (CGDI) started such a registry in 2006, but it currently (12/30/09) contains only 'WMS' and 'WFS', and does not seem to be maintained. The registry document is an xml/rdf document with bilingual (French, English) Dublin Core metadata describing the service types (xml document here)