We have been storing dissertations in the BDR for a while. Students have the option to embargo their dissertations, and in that case we set the access rights so that the dissertation documents are only accessible to the Brown community (although the metadata is still accessible to everyone). The problem is that embargoes can be extended upon request, so we really needed to store the embargo extension information.
We wanted to use a common, widely-used vocabulary for describing the embargoes, instead of using our own terms. We investigated some options, including talking with Hydra developers on Slack, and emailing the PCDM community. Eventually, we opened a PCDM issue to address the question of embargoes in PCDM. As part of the discussion and work from that issue, we created a shared document that lists many vocabularies that describe rights, access rights, embargoes, … Eventually, the consensus in the PCDM community was to recommend the PSO and FaBiO ontologies (part of the SPAR Ontologies suite), and a wiki page was created with this information.
At Brown, we’re using the “Slightly more complex” option on that wiki page. It looks like this:
<pcdm:Object> pso:withStatus pso:embargoed .
<pcdm:Object> fabio:hasEmbargoDate “2018-11-27T00:00:01Z”^^xsd:dateTime .
In our repository, we’re not on Fedora 4 or PCDM, so we just put statements like these in the RELS-EXT datastream of our Fedora 3 instance. It looks like this:
<rdf:RDF xmlns:fabio=“http://purl.org/spar/fabio/#” xmlns:pso=“http://purl.org/spar/pso/#” xmlns:rdf=“http://www.w3.org/1999/02/22-rdf-syntax-ns#”>
<rdf:Description rdf:about=“info:fedora/test:230789”>
<pso:withStatus rdf:resource=“http://purl.org/spar/pso/#embargoed”></pso:withStatus>
<fabio:hasEmbargoDate>2018-11-27T00:00:01Z</fabio:hasEmbargoDate>
<fabio:hasEmbargoDate>2020-11-27T00:00:01Z</fabio:hasEmbargoDate>
</rdf:Description>
</rdf:RDF>
In the future, we may want to track various statuses for an item (eg. dataset) over its lifetime. In that case, we may move toward more complex PSO metadata that describes various states that the item has been in.