f8.txt

Strong identifier or strong key (strong - no ambiguity about what they represent or represents one and only one resource, stable - a URI represent the same resource over time) - Uniform Resource Identifier (URI): a unique identifier to a node which can be accessible on the Web (global reference), provide a common syntax for naming a resource regardless of the protocol used to access the resource, but it does not restrict urirefs (URI reference) to being "real" data sources (i.e., a specific protocol doesn't need to be specified, or must exist on the Web).