OpenStreetMap

"Local knowledge" of every postbox in the UK is pretty impressive :)

(OK - I know that's not what you meant...)

What value does adding a wikidata tag perform here? Presumably this is via the name suggestion index.

This tag was mentioned on two wiki pages (not by me). Also, taginfo had reported 100+ cases of its usage before I committed more. In general, it looked like another effort of connecting OSM and Wikidata which is usually considered a useful thing. It wasn't me who started the effort, but my knowledge of Overpass and JOSM was enough to mostly finish it.

I agree that royal_cypher:wikidata tag is not of high importance. That said, consider it as metadata like check_date:* which helps people and tools to process and maintain OSM data.

The wikidata advice although on the wikipage for a long time is probably the personal opinion of a long-term wikimedian and wikidata enthusiast. Not necessarily a considered view of it's value in the community.

The problem with all such well-intentioned edits is that they push up the last edit date and version count for little value. This has the effect of making it harder to spot things which DO need checking at a local level.

Doing a basic join on value from OSM to wikidata works just as well as adding an additional key. The wikidata item already has an entry for the OSM key which effectively does this work already.

I believe we can't treat the date of a recent edit as check_date:* tags. Yes, this logic works in many cases. That said, check_date:* is the proper approach to the issue of stale data.

I agree that check_date:* tags aren't as widespread as they deserve to be. This seems to be the reason why you have to look at the date of the latest edit.

check_date is very much a tag only regularly used by StreetComplete (and for good reasons: I'm not going to mark every shop I see which hasn't changed with a check_date).

OSM is not fantastically well stuctured to allow capture of this kind of meta data, largely because a check_date increments the version count. Separate metatags might help, but that would require a new API call and database changes.