PUBLIC MARKS with tags uri & http

"[...] It seems that folks like Yahoo! and Twittervision offer different representations of the same resource using different URIs .xml, .json, .php, .yaml, etc. I’d say that’s arisen because users have little control over content-negotiation in their browser. Isn’t having the same resource identified by lots of different URIs an issue for the Semantic Web? [...]"

This document describes the "tag" Uniform Resource Identifier (URI) scheme. Tag URIs (also known as "tags") are designed to be unique across space and time while being tractable to humans. They are distinct from most other URIs in that they have no authoritative resolution mechanism. A tag may be used purely as an entity identifier. Furthermore, using tags has some advantages over the common practice of using "http" URIs as identifiers for non-HTTP-accessible resources.

Les URI comme localisation hiérarchique vs identifiant.