[Talk-transit] New proposal to store public transport data

[Richard Mann]

See http://www.openstreetmap.org/browse/node/533877725 for a not
untypical NaPTAN bus stop

ref is on a plate on the stop (and is the numerical equivalent of the
Naptan Code)
local_ref is on a plate on the stop, and is used to tell adjacent stops apart

My guess is that there are various coding systems, and they each need
to have their own tag, otherwise they'll get confused. The data user
needs to know the various tags if they want to use the codes.

I'd reserve ref for a unique id that can be validated on the ground
(if there is one).

Richard