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From: William Waites <ww@eris.okfn.org>
Date: Mon, 22 Nov 2010 14:39:31 +0100
To: List for Working Group on Open Bibliographic Data <open-bibliography@lists.okfn.org>
Cc: public-xg-lld@w3.org
Message-ID: <20101122133931.GL60158@styx.org>
(cross-posting a bit to the LLD XG to benefit from the insight of
people there that may not be subscribed to open-bibliography@)

* [2010-11-22 13:49:46 +0100] Makx Dekkers <mail@makxdekkers.com> écrit:

] I am not sure what you mean by "confusing in that it was a literal that
] was constructed like a URI".

This is not a question of right or wrong, but a question of best

] In the sample I see:
]     <dcterms:identifier>GBA164362</dcterms:identifier>
] and
]     <dcterms:identifier>URN:ISBN:1850877019</dcterms:identifier>
] Both are correct usage of dcterms:identifier (apart from the uppercase
] as you pointed out). In both cases the identifier is the (literal)
] string of characters. The second identifier is not just "constructed
] like a URI", it is a URI! 

Both are correct in that they conform to the range of
dcterms:identifier. The problem of the first is that it isn't obvious
what kind of identifier it is -- as it turns out it is the British
National Bibliography identifier (I think).

The second is not a URI, it's a literal. It won't be indexed in stores
as a URI, the sparql isURI and isLITERAL tests will treat it as a
literal, etc.

The reason to have urn:isbn: is so that it is at least possible to tell
what kind of a number that is, probably better to use a dedicated
predicate like bibo:isbn in which you don't need to fudge it with a
urn:isbn: prefix. 

] Yes, it may be confusing that you can use the URI in two ways: either as
] the (literal) string itself like here in dcterms:identifier, or as a
] pointer to a resource which you would do if you used it in
] dcterms:relation, for example.
] Both
]     <dcterms:identifier>someURI</dcterms:identifier>
] and
]     <dcterms:relation rdf:resource="someURI" />
] are correct -- the URI just plays different roles.

Correct in terms of "are valid RDF" and "conform to the defined
semantics" but apart from some obscure cases involving reification, I
think it is not a good idea to have literals that look like URIs
without very good reason.

William Waites
9C7E F636 52F6 1004 E40A  E565 98E3 BBF3 8320 7664
Received on Monday, 22 November 2010 13:40:00 UTC

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