I operate an app which is a data consumer of administrative boundaries. While processing Norway boundaries, I discovered that there are some admin_level=9 boundaries with tagging that indicates that the boundary is no longer valid. For example, Rennesøy and Finnøy.
Other than the note tag, there is no obvious way for a machine to know that these are no longer valid boundaries. I only want to consume boundaries that still exist, not old ones How should I interpret these objects? Could they be re-tagged as something else, like boundary=historic perhaps?
The was:xzy tag only applies to the key that you put it on. It’s completely valid, for example, to have was:place=town and place=city on the same object. It would be that “this used to be a town but now it is a city”. It also says nothing about other tagging. So the current combination on these objects would mean “it’s currently an administrative boundary which used to be a municipality”. To capture the fact that something used to be an administrative boundary, you would want to replace boundary=administrative with was:boundary=administrative. Otherwise the intent is lost.
Now, for my specific problem, I just did an overpass query and found that all of the admin_level=9 in Norway have that was:place tag, so that tells me I can just ignore level 9 in Norway for the purpose of my app. But, I would recommend some type of tagging change above so that the next data user isn’t confused.
Rennesøy and Finnøy is historic municipalities (admin_level=7), as the note suggest, but new boroughs (admin_level=9) have been created in their place, under the city of Stavanger. The same relations has simply been reused. Perhaps new ones should have been crated instead.
How should I interpret these objects? Could they be re-tagged as something else, like