On 01.09.2015 05:11, Stas Malyshev wrote: ...
That's a very interesting point, I think this can be handled by establishing:
- Types/classes of units, such as "measure of length"
- Designated standard unit - e.g. "meter" is a "standard measure of
length". 3. Conversion properties - e.g. "foot" is 0.305 "meters" 4. Having RDF exports contain values converted to standardized measures
- i.e. every quantity that has unit that is "measure of length" will
also have a value expressed in "meters".
Then reconciling data between instances would be just reconciling properties for the above (which can be made easier by finding some existing ontology featuring units and relating to it), and then matching entities for standard measures.
Mapping a unit entity to a (unique) external IRI could be done by a suitable property that is then used during RDF export, as we already do with other special properties. It still leaves each wiki with the (huge) effort of defining all units, their labels, and conversions manually.
It would be great if it would be possible for a Wikibase site to (also) use the Wikidata unit entities as if they were local entities. One could probably just fetch their labels and conversions through the API, which I suppose the UI is already doing now for units that are "local". This feature would be a bit like MediaWiki's InstantCommons for Wikidata units. Ideally, this would lead to a situation where most units in most Wikibase sites are taken from Wikidata, with only a few special things defined locally as needed.
Markus