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- Wikidata has a 301 redirect from http to https URIs in place but retains http URIs as "Concept URIs", i.e. in RDF data.
- schema.org vocabulary retains http in the URIs, has a 301 redirect from http to https URIs and a triple in the RDF data connecting the two with schema:sameAs, e.g.
schema:CreativeWork schema:sameAs <https://schema.org/CreativeWork>. (https://schema.org/CreativeWork.ttl, Status 2019-02-01) In the FAQs there is a statement that both, http and https are fine right now and that over time migration to https is intended (Status 2109-04-16) - Library of Congress has so far decided not to switch URIs to HTTPS due to disruption but also lack of capacity to make a final decision. There are plans to review the decision and investigate further (Status February 2019)
- DOI URI prefixes are https://doi.org/, see http://www.doi.org/factsheets/DOIProxy.html#encoding
- ISNI URI prefixes are http://isni.org/isni/, see http://www.isni.org/how-isni-works
- ORCID URIs prefixes are https://orcid.org/, see https://support.orcid.org/hc/en-us/articles/360006897674-Structure-of-the-ORCID-Identifier
[Update 2019-03-12:] German National Library (DNB) decided to switch all URIs in domain d- nb.info to https in October 2019
The National Library of Sweden added new canonical "https" URIs for formal resources in the domains id.kb.se and libris.kb.se at the occasion of the introduction of their new infrastructure Libris XL. (The old "http" URIs are maintained using owl:sameAs in this new system. These will be issuing HTTP redirects to the new URIs as soon as possible.) (Status March 2019)
tbc