Extend the License schema / create a requirement/clause schema 1..n to licence

[proccaserra]

Following a request by George Alter and email discussion

[agbeltran]

+1 to adding a relationship between License and a requirement component.

I would also consider including also Permissions and Prohibitions, as per the RDF representation of Creative Commons

cc @altergc

[altergc]

I would have preferred to include Requirements, Permissions, and Prohibitions as separate components, but I don't think that it is feasible based on what I am seeing in the dbGaP agreements. The dbGaP data use limitation (DUL) codes mix permissions and prohibitions in the same code. For example, the Health/Medical/Biomedical code (HMB) by definition excludes research on ancestry. So, it is both a permission and a prohibition. DUO is carrying this pattern forward from DUL. I experimented with a scheme that would separate codes like this into their parts, but it did not look good. Furthermore, I don't think that DATS should be parsing items that it receives from other sources.

This will probably get sorted out by more detailed ontologies, like ADA-M. But I think that it is better for DATS to use a broader component that includes all three types.

[agbeltran]

The discussion in DCAT revision about licenses is relevant here: w3c/dxwg#114