Levels of labels in address details

[molokanov50]

Hi team,

According to the documentation, place output offers a set of labels which are used to describe address details. Here, https://nominatim.org/release-docs/develop/api/Output/#addressdetails, the labels are grouped by their administrative significance, so state and region appear to have the same administrative level.
In the same time, there are such address objects: https://nominatim.openstreetmap.org/search?q=novogireyevo&format=xml&addressdetails=1
We can see that state label actually corresponds to a region, and region label corresponds to a federal district, which, for Russia, is more generic than region. In other words, both labels of the same assumed level (from the viewpoint of the documentation) appeared simultaneously, and region is more generic than state. The same has place for suburb and city_district.
So are the labels somewhere described with some integer-value levels? Does the mapping change from country to country - maybe, for some countries, region can be, oppositely, more specific than state? Where can I find this mapping?

[lonvia]

The labels are derived from OpenStreetMap tagging practises and not from country-specific designations. They are assigned according to the place type and admin_level. See this blog post for some insight.

If you need access to the integer admin_levels as mapped in OSM, I recommend using the geocodejson format together with addressdetails=1. This returns an admin field with integer boundaries.

For example https://nominatim.openstreetmap.org/search?q=novogireyevo&format=geocodejson&addressdetails=1 has:

...
"admin": {
  "level3": "Central Federal District",
  "level4": "Moscow",
  "level8": "Novogireyevo District"
}
...