[Tagging] Why using place=city for legal status is a bad idea

wynndale at lavabit.com wynndale at lavabit.com
Sun Dec 27 15:51:19 GMT 2009

A sentence was recently added to the wiki
[http://wiki.openstreetmap.org/wiki/Key:place] stating that the tag
place=city should be used for legally defined cities in countries where
such a status exists. This is superficially attractive but it gives rise
to problems. The key issue is that place names, like roads, naturally form
a hierarchy, and that the tag place=city is similar to the tag

For instance, the category in the United Kingdom includes Wells, which has
a population of 10,000 and which the Collins New World Atlas leaves out of
its 1:3,000,000 map of the British Isles. This is similar to the road
category of Bundesstrasse (nationally maintained road) in Germany, which
includes some quite small roads while omitting ones that are much more
important. If (say) highway=trunk was used for such roads a map generated
only from OSM data without an outside cheat sheet gives a warped idea of
roads in Germany; OSM solves this problem by not using a distinct level
for these roads.

Using tagged population figures as a substitute to guide renderers has
been suggested but it brings its own problems because people will expect
them to be more broadly useful and figures may either be out of date or it
may be unclear what area is being counted.


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