[OSM-talk] Maritme borders

Steven te Brinke s.tebrinke at student.utwente.nl
Fri Jan 2 19:58:45 GMT 2009

IMO, the proposal of Gustav is better, because maritime borders clearly 
are administrative. Martijn suggests that there is a clear difference 
between country and maritime borders. However, it are different 
properties of a border: a border can be one or both. The half of the 
Dutch country border is a maritime border. So I would propose to use 
boundary=administrative on all maritime borders and use another tag to 
distinguish them.
Currently, borders are distinguished by admin_level. The wiki tells 
about admin_level: "admin_level 
<http://wiki.openstreetmap.org/wiki/Key:admin_level>=1 to 10 has been 
introduced in order that different borders can be rendered consistently 
among countries (doing this based on border_type would require knowledge 
of their hierarchy in each country)." Based on this information, I 
conclude that every border has a border_type, but we tag it as 
admin_level for convenience. For example: border_type=province and 
inside(The Netherlands) implies admin_level=4. We mainly tag the 
admin_level only, because that one is the easier for rendering, but we 
think about it as border types and sometimes tag border_type too. So I 
would propose to use border_type for any border that has no admin_level 
defined. Thus the territorial sea will have admin_level=2 because it's a 
country border, but any other maritime border will only have border_type 
set. That works quite well with the current tagging: border_type is 
optional when admin_level is set, required otherwise. Also for rendering 
it's no problem: render borders based on admin_level and when that one's 
empty, use border_type. The only thing that remains is: which 
border_types are possible? Probably exclusive_economic_zone will be one 
of them.


Gustav Foseid schreef:
> On Thu, Jan 1, 2009 at 6:45 PM, Martijn van Oosterhout 
> <kleptog at gmail.com <mailto:kleptog at gmail.com>> wrote:
>     boundary=maritime?
> or something like:
> boundary=administrative
> admin_maritime=territorial
> ?
>  - Gustav
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