Proposal:Boundary segment

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If you want to tag boundaries representing a closed ring/area please see Relation:boundary

Boundary segments are made with the generic relations: type=multilinestring and are used for grouping ways to form a bigger logical linear boundary making the border between two regions. Such as the border between Italy and France but can also be used on any type of boundaries (administrative, protected_area, military, maritime, etc.)

(See Relation:multilinestring for more details on the construction)

Relation Tags

Key Value Discussion
type multilinestring
name * The name of this boundary if applicable (ex: France/Italy boundary)
boundary administrative / protected_area / ...
admin_level the admin level
any applicable

Relation Members

Way or Node Role Recurrence? Discussion
way (blank) one or more the multiple ways representing one linear border
relation (blank) zero or more Other relations of type=multilinestring could they be boundaries as well or other nature

The sum of ways + child relations's ways + child's child's relation ways + ... should form a linear connected list of ways

Note : Ways without a role shouldn't form a closed border. For closed border, see Relations:boundary.

Why ?

Why not use only the closed relation Relations:boundary (or type=multipolygon relations) ?

  • Processing time is high and might lead to problems if all the member ways are in one single relation
  • Editing is very hard due to huge list of members
  • When a boundary segment is created, it can be reused by the two relations forming the two countries/regions
  • Easier to represent or use the boundary between two countries/regions as it is only one relation

Why not ?

Why use the current closed relation system?

  • it's approved
  • a lot of people use it for about six years now
  • JOSM is good at handling even the biggest country borders worldwide; the relation editor in JOSM works fantastic, great compliment to the developers!
  • It will be harder to verify the integrity of borders (at least this one will stop working:
  • A lot of people at this moment rely on the current approved relation system for mapmaking purposes
  • It requires an enormous change management project to make this work for all country/region/city etcetera borders
  • It doesn't solve the real problem: changing borders should require a verification process by an editor because border relations are broken up too often; OSM is yet (2012) far away from this Wikipedia level of matureness

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