Non-standard multipolygon semantics
The documentation as currently written gives special semantics to multipolygons (beyond merely representing areas) by requiring that platform edges have to be relation members. I feel we should avoid these kinds of "side effects", as it means that multipolygons and other areas could no longer be parsed in a generic way by data consumers, and might no longer work the same way if we were to finally implement an area element in the API.
To remedy this, I suggest to only require that edges share nodes with the platform area. Multipolygon members would trivially fulfill this, so it wouldn't require changing how the platforms are actually being mapped. --Tordanik 18:00, 26 February 2018 (UTC)