User:Skybunny/Boundaries

Feature : Skybunny/Boundaries

Description

Boundaries mark the borders of areas, mostly political, but also of other administrative areas.

Group

Boundaries

Tags

boundary=*

On a geographic map, boundaries define the outer edges of two dimensional shapes.

Specific to OpenStreetMap, boundaries refer to relations with several ways (and possibly nodes) as members, such as multipolygons (Relation:multipolygon), or boundaries (Relation:boundary). Collectively, the ways, nodes, and relation are used to describe a two dimensional shape, possibly with one dimensional coordinate node hints as relation members.

++ The consensus in OSM editing today is that a boundary is described using a relation. A boundary relation consists of:

• The relation itself
• One or more member ways that comprise the shape of the boundary
• One or more member nodes that describe other aspects of the relation (such as the optional-to-use label member)

An original accepted usage was to apply the boundary=* tag to areas. As early as 2012, this use had fallen out favor, because OSM Areas, by themselves, cannot have associated nodes. Historical experience has shown that relation member nodes are extremely useful (especially for machine data consumers) to help interpret and render boundaries created in OSM, whether to provide additional information, or for backwards compatibility.

See the boundary relation for best practices for creating boundary relation shapes.

Further reading

• boundary=*, the key which classifies a boundary relation by its type
• boundary=administrative, a subset of the above specific to administrative boundaries
• Relation:boundary

See also

• Places, and place=*, a similar tag set and structure for human settlements and other features

Downloads

• OSM Boundaries by User Wambacher
• Boundaries as download by mapzen.com