work in progress
This page tries to list features, for which there are several tagging systems in use. These have emerged out of lacking documentation, or lacking discussion. Some of these are minor issues as the tagging systems don't conflict with other uses, others might become a problem where two editors nearby use/prefer different systems.
Majority of highway=bus_stops have been as node to the side of the road. Recently approved public transport proposal recommends transitioning to public_transport=platform to the side of the road and public_transport=stop_position on a node that is part of the road.
When sidewalks are not drawn separately, both
describe whether the road has a sidewalk(s). The value yes has also been used, but doesn't convey whether it equals both or just at least on one side.
When sidewalks are drawn separately, there is, on the way marking the center line of the sidewalk,