Reference on the Web is the same as reference off the Web
¥This is simply obvious, I claim. The Web is a transport mechanism for representations. But how a representation represents, and how the names in it refer, has nothing particularly to do with how the representations are transported. ( Korzybsky: ÒThe map is not the territoryÓ.)
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¥Reference has to do with the meaning of texts, broadly construed. The Web has extended the notion of text to hypertext, but adding markup to a text does not change its meaning qua text (*); and the use of URIs in RDF/OWL does not even qualify as markup. With a few exceptions (owl:imports, rdfs:seeAlso, etc,.) the Semantic Web languages would operate exactly unchanged if the identifiers in them were not URIs at all, and if the Web did not  exist.
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¥(*) One exception might be the ÔgesturalÕ use of a hyperlink , as in Òfor more on Julius Caesar, see <a href=Òhttp://www.ihmc.us/users/phayes/Julius.htmlÓ>here</a>, where the word ÒhereÓ refers to the accessed entity, much as one might gesture at a library shelf in ordinary conversation. But even such uses, while new in written language, have clear roots in spoken language use.