This is a description of relations used in the public transport tagging scheme. There are 2 variants, both regarding public transport stops, stations, halts, or similar: stop_area and stop_area_group.
A stop area consists of everything regarding the embarkation and disembarkation of a specific public transport vehicle or service. For example, a specific railway line, the adjacent platform, services on that platform, and information describing it (platform number, etc.).
public_transport=stop_area_group was not part of the proposal Proposed_features/Public_Transport and its definition and necessity is unclear. Consider to not use such relations.
The public_transport=stop_area tag is de facto used as part of a relation to group stop areas that make up a public transport interchange: for example, a multi-modal interchange for buses, metros and trains.
Tokyo station (bus, metro and train), Tokyo: 93335719333571
Some cities also use public_transport=stop_area_group for interchanges between two lines on the same network, such as Piccadilly Circus tube station in London (77041387704138): in those cases, each line has their own stop areas relation.
public_transport
