Tr:Relation
Multipolygon
Multipolygons are one of two methods to represent 
areas in OpenStreetMap. While most areas are represented as a single 
closed way, almost all area features can also be mapped using multipolygon relations. This is needed when the area needs to exclude inner rings (holes), has multiple outer areas (exclaves), or uses more than ~2000 nodes.
In the multipolygon relation, the 
inner and outer roles are used to specify whether a member way forms the inner or outer part of that polygon enclosing an area. For example, an inner way could define an island in a lake (which is mapped as relation).
Bus route
Each variation of a bus route itinerary is represented by a relation with type=route, route=bus and ref=* and operator=* tags. The first members in the route relation are the nodes representing the stops. These are ordered in the way the vehicles travel along them. Then the ways are added. In PT v2 the ways form an ordered sequence, along the stop nodes. The ways don't get roles. If they form a continuous sequence this is apparent from the continuous line along them (in JOSM's relation editor).
Other Examples
- Relation:boundary to exclusively define administrative boundaries
- Relation:restriction to describe a restrictions such as 'no left turn', 'no U-turn' etc.
- see Types of relation and Category:Relations for more
Tools
- JOSM/Advanced_editing#Relations: Work with relations in JOSM
- Potlatch 2/relations: Work with relations in Potlatch
- Show a relation: Example id=11
- Show history of a relation: Example id=11
- Rendering a relation: Example id=11
- OSM Relation Analyzer
- Relation Check
- Relation Diff
- Relation lists
- Search for a relation: http://ra.osmsurround.org
- Visualise a relation on a map
- Rel2gpx
Please list routing apps here, that are able to follow a relation route (like for pilgrimages)
- No app known yet.
See also
- Ana makale: Types of relation