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People seem to use either dct: or dcterms: as a prefix for the the http://purl.org/dc/terms/ namespace. Is there any guidance on which is "right"?

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Please note; I know the difference between dc and dcterms. My question is if there is any guidance on which is the preferred prefix to use. – Christopher Gutteridge Mar 14 at 17:18
Added comment on the lack of guidance and comment that that is a good thing. – Egon Willighagen Mar 14 at 17:24
What bugs me is that most other namespaces have a standard prefix, and this one has two. Hardly life and death, perhaps I'm looking for a foolish consistency, but it's bitten me once or twice. – Christopher Gutteridge Mar 15 at 10:09

5 Answers

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The most popular prefix, according to Swoogle, is dcterms.

Here are the top ten prefixes and their frequencies for this namespace in Swoogle's collection.

  216088  dcterms
   17476  dcq
   10047  terms
    4514  dct
    2250  dc
    1129  ns3
     526  ns4
     520  dcterm
     274  ns2
     163  ns6

When there is a prefix that's preferred by the community it's good to use it to improve the readability of the serializations.

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Gotta love an answer with data to back it up! – Christopher Gutteridge Jun 22 at 7:35
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I am not aware of guidance for prefixes, and as explained below, there should not be such guidance.

It does not matter which prefix you use (there is no right prefix), as long as it is properly tied to the namespace. These specs use two prefixes (dc and dcterms), but are merely used as shortcuts to their two matching namespaces (http://purl.org/dc/elements/1.1/ and http://purl.org/dc/terms/).

It is important to note that namespaces do not easily conflict, but prefixes can. It is therefore important that the actual prefix used does not matter. That said, there is a trade off between length of the document (short prefix) and human-readability (longer prefix).

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excellent points +1 as you said the prefix is largely irrelevant - it's the namespace URI that matters – Rob Vesse Mar 15 at 11:10
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Technically, any namespace will do. All interoperability is done in terms of the URL.

If you're generating examples for newbies, dcterms is probably easier to remember / grok.

If you're generating a 50 GB dump of data, dct saves you four characters per row (but compression probably gets you most of that back).

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No, any prefix will do. Only one namespace is correct. – Egon Willighagen Mar 14 at 10:04
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There is, in the official spec:

Implementers may freely choose to use these fifteen properties either in their legacy dc: variant (e.g., http://purl.org/dc/elements/1.1/creator) or in the dcterms: variant (e.g., http://purl.org/dc/terms/creator) depending on application requirements. The RDF schemas of the DCMI namespaces describe the subproperty relation of dcterms:creator to dc:creator for use by Semantic Web-aware applications. Over time, however, implementers are encouraged to use the semantically more precise dcterms: properties, as they more fully follow emerging notions of best practice for machine-processable metadata.

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This quote does not answer the question. – Egon Willighagen Mar 14 at 10:11
I think it does. If the spec uses the dcterms: prefix for the namespace the OP asked about, when why wouldn't you use it? "the dcterms: variant (e.g., purl.org/dc/terms/creator)"; - what's unclear about that? – Thomas Kappler Mar 15 at 9:30
The question is asking about the conventions around the namespace prefix to use, not the property URIs. So while your information is correct, it's not answering the question. – Ian Davis Apr 15 at 10:54
@Egon and Ian: It is answering the question, because it shows that DCMI themselves use “dcterms” and not “dct” when they talk about the purl.org/dc/terms namespace. – cygri Jun 22 at 5:37
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Just use dc (and dc11 or dc10 for the old versions). Versioning via urls wasn't a good idea, and I doubt it will change from now on.

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