RFC 2068:Hypertext Transfer Protocol -- HTTP/1.1
RFC-Ref

Uniform Resource Identifier


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... methods that indicate the purpose of a request. It builds on the discipline of reference provided by the Uniform Resource Identifier (URI) [3][20 ...


... Uniform Resource Identifiers ...
... URN). As far as HTTP is concerned, Uniform Resource Identifiers are simply formatted strings which identify--via name, location, or any other characteristic--a resource. ...


... The Request-URI is a Uniform Resource Identifier (section 3.2) and identifies the resource upon which to apply the request. ...



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