[OSM-talk] open question about boundaries sharing nodes with ways or nodes

[Colin Smale]

Boundaries are often downloadable from authoritative sources. The
downloadable data is however not always the legal definition of the
boundary, but derived from that definition - either by surveying if the
definition is descriptive, or by generalisation as the full level of
detail is too much for the download (for whatever reason), or by
reprojection (if the boundary is legally defined in a different datum
such as OSGB36). But the result of all that is a set of coordinates
which we effectively cannot dispute. 

The boundary is where the government says it is... 

//colin 

On 2015-10-14 12:17, Christoph Hormann wrote: 

> On Wednesday 14 October 2015, Maarten Deen wrote: 
> Academic detail. "Is" the boundary the river, or is the boundary a
> thing
> its own right, the geometry of which is described by the river? I
> think you can argue either way. 
> And the legal part can be different too. It can be that the boundary
> is the river and it will change when the river changes, it can also
> be that the boundary has been defined as the river at a point in time
> and if the river changes after that point, the boundary does not
> change with it.

Note practically this is usually 'academic detail' as well - most 
demarcated boundaries are not represented by actual demarcation points 
in OSM but by some approximately drawn line.  In case of boundaries at 
rivers this rarely gets worse when you attach the boundary to the 
accurately mapped river.  Examples:

http://www.openstreetmap.org/#map=15/32.0077/35.5299
http://www.openstreetmap.org/#map=14/0.7489/29.9702 
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