Marko Mäkelä <marko.makela@iki.fi> writes:
That's an interesting point. In the US, around me, there really aren't such assumptions. Instead, a lot (area of land that can be bought and sold as a unit) has an address, generally taken from a public or private way that borders the lot.
I see. I have some knowledge of the administrative system of properties in Finland. I do not think that street names play any role there. A property may have been assigned an arbitrary name by its owner, but it always has a registration number that uniquely identifies the lot. If the lot is split, I guess that all parts of it will get a longer registration number (adding some suffix to the original number). Nowadays, the fully qualified registration number should start with the NUTS (Nomenclature of Territorial Units for Statistics) prefix of the municipality.
Streets may be renamed or renumbered (seldom, but possible when lots of properties have been split and new houses built, for example). This would not affect the registration numbers of the properties. BTW, I don't think that the registration numbers will or should be put to the OSM database. They are only relevant when buying or selling properties. It should suffice to have the administrative boundaries of the suburbs or villages.
We also have parcel numbers which are more or less similar (town, zoning map sheet name, parcel number, and suffix on subdivision). We also do not use them in addressing and generally no one has an idea unless they are dealing with applications under zoning rules. So I think until we have an example of addresses being based on these, mkgmap can ignore them.
In Finland, when the same street goes through multiple municipalities, it usually changes names at the border. This is unlike what I saw in the US: El Camino Real in California would be called that for the whole way, and you would have to pay attention when crossing borders, because there could be multiple identical house numbers, maybe some tens of miles apart. Sure, in every country, you will have common street names such as "Main Street" or equivalent in every town, but those would typically not be part of a major route. However, this should not be a problem for the Garmin format. El Camino Real would be split to sections at municipality borders, and each section would be assigned its own house number data.
The US is highly variable and both styles exist. Around me, road names often change at the town border, and if they don't the addresses usually reset. For extra confusion, roads are named for the town they go to, so you can be on Lexington Road in Waltham and after crossing be on Waltham Road in Lexington. Agreed that this doesn't cause mkgmap/garmin problems.