[OSM-talk] Polygons with holes (rivers, lakes etc)

[Jon Burgess]

Representing areas with holes is tricky and not well understood. The
JOSM validator plugin incorrectly flags them as unordered ways. 

I would explain how to represent them correctly using a single way with
multiple disconnected internal loops but I realise this is going to
change when the 0.5 API is implemented this weekend so I'll hold back
until the new relationship scheme is deployed.

In the interim, if you see something which looks like a polygon with
some holes (e.g. a lake with an island in the middle) please do not
attempt to fix it by re-ordering the segments or splitting it into
multiple ways. Many of the AND water polygons have been broken by people
trying to do this.

	Jon