After merge, flag conflicting tags #908

jfirebaugh opened this Issue Mar 5, 2013 · 6 comments


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OpenStreetMap on GitHub member

Split from #435, where a concern was raised about concatenating tags with ;.


P2's (imperfect but good enough) solution is a little warning triangle and red text whenever it finds a tag containing a semicolon, absent a list of keys where it's ok.


I would say that adding manually a semicolon should not trigger a red sign (at least not more than a new and un-documented value).
But definitely, a merge operation should be guided to reconciliate tags, probably with a reconciliation interface of some kind (keep right, keep left, keep both with a semicolon).

I would say that a sophisticated merge UI is outside of iD's scope, at least for the time being. I suggest we implement something along the lines of what P2 does.


If you merge a foo=bar way with a foo=baz way you get foo=bar; baz. If you then merge it with another foo=baz way you get foo=bar; baz; baz. This makes merging sensitive to the order of ways merged.

A more sensible solution would be to split on ;, merge the lists, then re-join with ;.

OpenStreetMap on GitHub member

Good point. Can you open a separate issue for that?


If a merge UI is outside iD's scope it may be worth special-casing yes and no. Clearly a result of oneway=yes;no from merging is absurd. I am not sure what a good solution is.


I should add here my concerns expressed in #435.
First, a lot of tools does not the the semicolon separated value into account.
Secondly, I'm afraid an easy merge tool without any confirm of any kind could easily lead to mistakes.
Merging an element with tags with one without is OK, but I can't imagine other examples.

Could somebody elaborate the Tiger case? Maybe we should concentrate on this.


TIGER is not mentioned in this bug. What TIGER case are you talking about?

If it's the TIGER case in #435 (comment)

For an extreme example, check out what happened with the TIGER import in Hawaii: just about every road is in multiple (sometimes hundreds of) pieces. I'd hate to have to do cleanup there without being able to merge them

I believe that was an example of why merging ways is a necessary. It isn't unique to TIGER. There are plenty of places where you need to join overly split ways.

I just used the merge tool for moving addresses from points to areas. Moving POIs from points to building areas for single-purpose buildings is fairly common.

There are plenty of other reasons why some method to join ways is important. In any case, this issue is about how to handle conflicting tags after merging, not the merging itself. #435 seems more appropriate for what types of merges should be possible.


As long as users or iD are not made aware of the damage they cause, iD should not be allowed to merge ways at all.
Ways may seem overly split, but in many cases there is a reason why they are split (Membership of different relations).


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