we should tag the node where a motorway link diverts from the main road:
highway = motorway_junction
ref = [number of exit (where they apply)]
name = [name of the junction (optional)] e.g. Κομοτηνή Ανατολικά, Κόμβος Λαγκαδά
we tag the motorway link:
destination = [destination of the link] (this also applies to other roads as well)
destination:lanes = [destination 1]|[destination 2]
*there are numerous discussions that suggest destination is better than exit_to
*it appears destination:ref is a proposed tag
It has been a global practice to tag nat_ref or ref to the roads, partly due to varying importance for each stretch of road, but I still think nat_ref should just be ref since it’s currently the only road numbering system around.
I agree, and not only for the reason that you you mentioned, there are other issues too (like rendering).
I think ( in my opinion) that ref tag is a primary tag (mandatory) and should be always present on roads.