[Tagging] Boundary Relations. What's a subarea used for?

[Colin Smale]

I consider them a significantly useful feature. 

They are used to indicate an administrative relationship. Because of
exclaves/enclaves and the sometimes strange system in the UK a purely
geometric approach would not always produce correct results. Use of
"is_in" is very error-prone as it relies on string matching. 

Furthermore, not every data consumer will have the hardware, software,
knowledge and patience to recreate the administrative hierarchies based
on geometric information. So before the subarea info can be removed,
please suggest a workable alternative for the small man. 

Colin 

On 2015-01-08 02:37, Toby Murray wrote: 

> +1 from me. 
> 
> I believe the whole U.S. boundary relation actually contains all the state boundaries as subareas. I've never understood the use. I guess a couple of times it made downloading the state relations for editing easier but I have other ways of doing that... 
> 
> Toby 
> On Jan 7, 2015 7:23 PM, "Dave F." <davefox at madasafish.com> wrote:
> 
>> Hi
>> 
>> This UK county boundary (admin level = 6):
>> http://www.openstreetmap.org/relation/57533#map=9/51.1854/-1.8237 [1]
>> 
>> contains nested boundary relations (tagged with role=subarea) with numerically higher admin levels:
>> http://www.openstreetmap.org/relation/3410643#map=13/51.3398/-2.2428 [2]
>> 
>> Are they relevant? If so, what are they for? The wiki suggests they're superseded:
>> http://wiki.openstreetmap.org/wiki/Relation:boundary#Relation_members [3]
>> 
>> To me, subarea appears to be used in a similar way to the superseded 'is_in' tag, For the same reasons that tag was deprecated, mathematics & the admin_level tag can be used to determine if one polygon is inside another. They seem to be purely extra baggage
>> 
>> Am I missing something or can these nested relations be removed?
>> 
>> Cheers
>> Dave F.
>> 
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Links:
------
[1] http://www.openstreetmap.org/relation/57533#map=9/51.1854/-1.8237
[2] http://www.openstreetmap.org/relation/3410643#map=13/51.3398/-2.2428
[3]
http://wiki.openstreetmap.org/wiki/Relation:boundary#Relation_members
[4] http://www.avast.com
[5] https://lists.openstreetmap.org/listinfo/tagging
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