I do think TfL needs to decide what the dotted lines mean. “Walkable and has an OSI” is one definition, but equally it might be useful to someone to know a destination station is near another so they can use a more convenient route. For example, Battersea Park and Queenstown Road Battersea – there are no rational interchanges anyone would want to make but it could be useful for journey planning purposes to know of the proximity.