The obvious choice as a metric are the hypertext references as described above, but others such as document content overlap are imaginable. People see each other if the visibility overlaps 5. Objects are identified by type and name. Names are globally unique for each object type. The name will usually be tailored to the object type for better readability and to simplify addressing of external resources.
Locations are the most important resource external to the dynamic neighborhood model.
URLs are used as names of Location objects. Each object has instance variables to store individual information about the object. Part of the information such as the name is entered by users. Some information is extracted by various means and the third part is computed by the service at run-time. Icon and nickname represent persons at the user interface level.