Check for two or more multipolygons sharing the same outer way


JOSM validator is marking as an error when two multipolygons neighbors are side to side. ex. I have a forest multipolygon (role=outer) next to a grass multipolygon (role=outer). They share one side of each’s outer polygon.

Is this a mistake? You cannot have different multipolygons sharing the same outer way position?


I don’t know if it is actually considered a mistake but I know that I find making changes in places where multiple lines or polygons share the same nodes makes things more difficult.

What I prefer to do in cases like this where two land cover polygons touch one another is to make them into multi-polygons and then have the boundary between the two a separate way that is included in both multi-polygons.

What error message do you get?

It is not an error for multipolygons to share ways, but it can be that there are other errors. Which multipolygons give the error?