OSM: World Map or Set of Local Maps?
Pecularities of National Mapping
Each country has peculiarities, and osm data is no exception. It becomes a big problem, if you need osm-based map of the world, e.g. routable map for PNA.
I will tell about local mapping rules and techniques, mainly about Russia in comparison with Europe. Tagging of common objects, address schemes, road classification, and other areas.