# Third-party data & attributions

TREK bundles and uses third-party data that requires attribution.

## geoBoundaries — country & sub-national boundaries

The Atlas map's administrative boundaries (admin-0 countries and admin-1
provinces/counties), shipped at `server/assets/atlas/admin0.geojson.gz` and
`server/assets/atlas/admin1.geojson.gz` and generated by
`server/scripts/build-atlas-geo.mjs`, are derived from **geoBoundaries**.

> Runfola, D. et al. (2020) geoBoundaries: A global database of political
> administrative boundaries. PLoS ONE 15(4): e0231866.
> https://doi.org/10.1371/journal.pone.0231866

geoBoundaries is licensed under **CC BY 4.0**
(https://creativecommons.org/licenses/by/4.0/). Source: https://www.geoboundaries.org/

The bundled files are simplified (coordinate-quantized) and re-tagged with the
property names TREK consumes. Country borders (`admin0`) derive from the geoBoundaries
CGAZ composite; sub-national regions (`admin1`) derive from the per-country open
(gbOpen) release.

## OpenStreetMap — geocoding

Atlas reverse-geocodes places via the **Nominatim** service. Geocoding data is
© OpenStreetMap contributors, licensed under the Open Database License (ODbL).
https://www.openstreetmap.org/copyright

## OurAirports — airport reference data

`server/assets/airports.json` is built from **OurAirports**
(https://ourairports.com/data/), released into the public domain.