Relation:boundary

boundary

Description

for grouping boundaries and marking enclaves / exclaves .

Group

Properties

Members help

- inner - outer - admin_centre - subarea

Statistics

boundary=* relations can be used for grouping boundaries and marking enclaves / exclaves.

• Currently there are slightly different forms of boundaries in the real database:

• In Germany, Ecuador, Colombia and The Netherlands, boundaries have been imported as type=multipolygon-relations.
• In France, type=boundary with exclave/enclave/(none) roles and without subarea in the relation is used (please check FR:Relation:boundary).
• Currently the most common way according to the real database is to tag according to the rules of multipolygons, but use type=boundary.

• Software should support all types until fixed in database:

• type=multipolygon as well as type=boundary (An administrative boundary can be definitively recognised through the existing boundary=* tag)
• role=(blank),exclave for role=outer (note blank role is obsolete for multipolygons as well, but usually defaults to outer)
• role=enclave for role=inner
• role=admin_center for role=admin_centre
• Note: Even if names differ, semantics are equal

Relations are used in order to:

• Avoid name:left name:right, nation:right, region:right. This has been replaced by one relation per country/province/city etc.
• Make it easier to stitch all the parts of a border to each other
• Avoid multiple duplicated ways above each other.

Contents 1 Way Tags 2 Relation Tags 3 Relation Members 4 Examples 5 Helping Tools

Way Tags

Ways for borders will then only have boundary=administrative and the admin_level=* for the highest border (when a country, state, county are on the same way the admin_level would be 2). Old direction dependent tags like name:left=* / name:right=* can be removed.

Relation Tags

Key	Value	Discussion
type	multipolygon / boundary	in Germany, Ecuador, Colombia and The Netherlands, multipolygon is used (see talk page)
boundary=*	administrative	for a real boundary (sometimes in the middle of a river or 12 Miles away from coastline)
land_area	administrative	for coastline and real boundaries on land
name	a name
admin_level	the admin level

If you have a land-locked administrative area in the region you should set both: boundary=administrative and land_area=administrative. If the land_area is not the same as the boundary, make two relations, one with land_area=administrative and one with boundary=administrative.

Relation Members

Element	Role	Recurrence?	Discussion
	outer	one or more	The multiple ways that form the closed border
	inner	zero or more	Enclaves of this border - the multiple ways that form the closed inner borders
	subarea	zero or more	Refer to relations of sublevel boundaries inside this administrative level. Note : this role is optional, was not discussed, lots of people find it disruptive, its use in a number of cases may complicate editing boundaries and it hasn't been proved that it can help in something that wasn't allready possible with spatial queries.
	admin_centre	zero or one	Node representing the administrative centre, usually a town, city or village (depending of the boundary level, see place=*)
	label	zero or one	Node representing where to draw the label.
	(blank)	one or more	Old, use outer instead
	enclave	zero or more	Old, use inner instead
	exclave	zero or more	Old, use outer instead

Note: All ways should form closed rings making the border. For not closed, linear border, see Proposal:Relation boundary segment.

Examples

Baarle Nassau is a good use case for this relation. It has exclaves in enclaves. The exclaves in the enclaves of Belgium would just be added as exclaves to the relation of the Netherlands, the dutch province Noord-Brabant and the village border.

Tagging examples
C is A's enclave and B's exclave: <relation id="1"> <tag k="type" v="boundary" /> <tag k="boundary" v="administrative" /> <tag k="land_area" v="administrative" /> <tag k="admin_level" v="2" /> <tag k="name" v="light green country" /> <member type="way" id="AB" role="outer" /> <member type="way" id="AC" role="inner" /> </relation> <relation id="2"> <tag k="type" v="boundary" /> <tag k="boundary" v="administrative" /> <tag k="land_area" v="administrative" /> <tag k="admin_level" v="2" /> <tag k="name" v="dark green country" /> <member type="way" id="AB" role="outer" /> <member type="way" id="AC" role="outer" /> </relation>	C is A's enclave and B's exclave.
D is an exclave of B, but not an enclave of A since it also shares a border with C: <relation id="1"> <tag k="type" v="boundary" /> <tag k="boundary" v="administrative" /> <tag k="land_area" v="administrative" /> <tag k="admin_level" v="2" /> <tag k="name" v="light green country" /> <member type="way" id="AB" role="outer" /> <member type="way" id="AC1" role="outer" /> <member type="way" id="AC2" role="outer" /> <member type="way" id="AD" role="outer" /> </relation> <relation id="2"> <tag k="type" v="boundary" /> <tag k="boundary" v="administrative" /> <tag k="land_area" v="administrative" /> <tag k="admin_level" v="2" /> <tag k="name" v="dark green country" /> <member type="way" id="AB" role="outer" /> <member type="way" id="BC" role="outer" /> <member type="way" id="AD" role="outer" /> <member type="way" id="CD" role="outer" /> </relation> <relation id="3"> <tag k="type" v="boundary" /> <tag k="boundary" v="administrative" /> <tag k="land_area" v="administrative" /> <tag k="admin_level" v="2" /> <tag k="name" v="purple country" /> <member type="way" id="AC1" role="outer" /> <member type="way" id="AC2" role="outer" /> <member type="way" id="CD" role="outer" /> <member type="way" id="BC" role="outer" /> </relation>	D is an exclave of B, but not an enclave of A since it also shares a border with C.

See Relation:multipolygon#Advanced_multipolygons for more examples!

Helping Tools

• OSM Inspector
• Relation Analyzer
• Relation Check