Super-relation
A super-relation is a relation that contains other relations. Relations have initially been created to contain nodes, ways or areas and combinations thereof. From a technical point of view, relations are limited to 32,000 members to help facilitate processing by external tools.
A super-relation is referred to as a 'parent' in Osmosis. The hierarchical structure of super- and sub-relations is also called a 'nested relation'.
Usage
Nested relations are mostly used for structuring routes and less commonly boundaries. Other types of superrelations are rare because the good practice "Relations are not categories" limits their use cases. However, there is an effort to process them.
- Routes, especially national and international cycling and hiking routes should be rendered by Waymarked Trails
- boundaries are used to build a hierarchy tree by Boundaries.pl
- bi-directional linking to Wikidata on Property P402
An example of a super-relation is the EuroVelo Route 15 - Rhin bicycle way 2171555
2171555. It contains four members for each of the countries it passes plus one connection between countries. Each member is itself a super-relation and has many bicycle route relations as members each for a small part of this very long bicycle route.
See also
- Pros and cons of nested route relations: Relation:route#Creating super-relations for routes
- Implementation: Super-Relation/Implementation
- Relation:superroute - Used to group multiple routes into a parent relation
- Relation:route_master - Used to group individual (PTv2) public transportation lines into a parent relation.
- Route directions#One relation per direction