Am 02.12.18 um 02:28 schrieb Erik Paulson:
How do these external identifiers work, and how do I get something into one of these namespaces? (I apologize if I have missed them in the documentation)
Hi Erik!
You got the right idea. Sadly, this feature is not implemented yet. I don't know if there is any public documentation for this by now, but here is a very rough list of the stepping stones towards allowing what you want:
1) Enable Items and Properties that exist on Wikidata to be referenced from other Wikibase instances (repo or client) that can access the Wikidata's internal database directly, and do not themselves define Items or Properties (but may define other kinds of entities). This is implemented, but not deployed yet. It is scheduled to be deployed soon on Wikimedia Commons, as part of the "Structured Data on Coommons" projects (aka Wikibase MediaInfo).
2) Enable Items and Properties that exist on Wikidata to be referenced from other Wikibase instances (repo or client) that call Wikidata's web API, and do not themselves define Items or Properties (but may define other kinds of entities). This is relatively simple, but details about the caching mechanisms need to be ironed out. Ask Adam and Lydia about the timeline for this.
3) Enable Items and Properties that exist on Wikidata to be referenced from other Wikibase instances (repo or client) that call Wikidata's web API, and *do* themselves also define Items or Properties which are *distinct* from the ones that Wikidata defines. The spec for this is clear, but some old code needs to be updated to enable this, and some details about the user interface need to be worked out. Ask Adam and Lydia about the timeline for this.
4) Enable Items and Properties that exist on Wikidata to be referenced from other Wikibase instances (repo or client) that call Wikidata's web API, and may "augment" or "override" the descriptions of Items and Properties defined on Wikidata. There seems to be a lot of demand for this, but the details of the semantics are unclear, especially with respect to SPARQL queries. More discussion is needed.