dcterms vs dc11

[Natkeeran]

Fedora has the following pre defined namespace: PREFIX dcterms: <http://purl.org/dc/terms/>, which seems to be different from the dc11 defined here: https://github.com/Islandora-CLAW/islandora/blob/8.x-1.x/islandora.module#L72. Are they two different ontologies?

In Fedora (http://future.islandora.ca:8080/fcrepo/rest/), the dc prefix is mapped to http://purl.org/dc/elements/1.1/.

It seems like there is mismatch between how drupal is configured vs how Fedora is configured.

[dannylamb]

Yes, they are different ontologies. dcterms extends dc11, adding extra predicates. You also "should" use things not strings with dcterms. So there's objects for agents, titles, coverages, etc... dc11 in theory is less restrictive since it lets you jam in strings if you don't have another resource to point to with a URL. It all depends on how far you're willing to go for "compliance" with an ontology.

This is my basic understanding of it. @rosiel would know more.

And yes... the problem is that Drupal hardwires dcterms to use dc as a namespace prefix. So we could edit the .cnd file to line that up, but it most likely will confuse people. I'm 👍 to doing that, but others have expressed concern because traditionally it's been dc for 1.1 and dcterms for terms.

[rosiel]

Yep, what @dannylamb said! With a small correction regarding titles. The dc11 predicates don't have ranges, and the dcterms predicates sometimes do. Generally they lean to 'things not strings'. Agents, subjects, even formats are now things-not-strings. But dcterms:title has range Literal, so dcterms titles are an exception: strings-not-things.

The namespace shorthand dc is often ambiguous, which is why I prefer to use dcterms and dc11. If you read through http://dublincore.org/documents/dcmi-terms/ it helps to contextualize how they both exist together (i.e. there are two title properties in different namespaces, one with a range, and one without), and what the defined Classes are.

A historical note - you may run across old (>10years) literature that mentions "Qualified Dublin Core". That was an attempt to make some of the original 15 predicates more granular or typed, but it is obsolete and has been superseded by dcterms.

[Natkeeran]

Thank you for the feedback.