[Tagging] Interpreting "One feature, one OSM-object"

Andrew Harvey andrew.harvey4 at gmail.com
Wed Sep 22 12:19:35 BST 2010


Quite a number of times I've noticed a single way having the tag
boundary=administrative (I assume having come from the Australian ABS
import and being part of a larger relation marking some town or
suburb) but also having waterway=stream (for example
http://www.openstreetmap.org/browse/way/38128067).

My interpretation of the "One feature, one OSM-object" suggestion
would be that this is bad because the single way is being used for two
different purposes (representing a river, and representing an
administrative boundary). Because then you don't know which tags refer
to the river feature and which to the administrative boundary feature.

I would guess that the correct thing to do is have two different ways
which share the same nodes, one for the river and another for the
boundary. But I don't know how to duplicate an existing way like this
in JOSM.

If this is the agreed upon thing then it would be great if someone
could run a script that split the waterway tags from the boundary ones
into a new way. Having learnt from my last foray into running a
semi-automated script
(http://lists.openstreetmap.org/pipermail/talk-au/2010-August/007037.html),
I'll await feedback before rushing into writing one for this purpose.

It's not just rivers. For instance when I was adding an island, the
feature was already traced out as way
http://www.openstreetmap.org/browse/way/32317361 and then to seperate
the islet feature from the administrative boundary I added a new way
for this http://www.openstreetmap.org/browse/way/78499826. But I don't
know what's the best practice here.

This is really a general mapping question, not about the use of
specific tags so I'm not sure if tagging is the right list to post to,
but anyway.



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