Several people have raised the question of what admin_level values to use. There is no “right” way to use this tag, but it is worth your time to study the way that various countries use “admin_level” in the OpenStreetMap database.

Some conventions are that admin_level=1 is rarely used (it might be used for something like the EU or some other supranational group). Beyond this, there is a tendency mainly to use even numbers, thus in the United States, admin_level=2 is the national boundary, admin_level=4 is the states, admin_level=6 is counties, parishes or boroughs (depending on the state), and admin_level=8 is most independent town and city governments.

There is a very useful chart at the OSM wiki, here.

I decided to set up an experimental page in my user sandbox to see if there interest in creating a parallel for this OSM page for our OGF countries. You can access this experimental page here:

http://opengeofiction.net/wiki/index.php/User:Luciano/Sandbox/admin_level

[edit: I’ve consolidated the above to a general “tags” page idea: http://opengeofiction.net/wiki/index.php/User:Luciano/Sandbox/tags#admin_level.3D.3F]

As a matter of personal observation, you may choose what admin_level you want to use for a specific node or relation based on how you want it to render on the map (in either “Standard” or “histor” style), but I don’t think that’s “best practice.” Let’s focus on making maps consistent with the OSM standard, and I think we can expect whatever rendering issues there are to “catch up” over time.

My personal experience is that if I take the time to correctly set up my administrative relations with all the appropriate data, it renders quite acceptably in the “Standard” layer.

Post comments, feedback or questions here or on the talk page there.

Happy mapping!