# Credits & third-party licenses

greyline itself is licensed **GPL-2.0-or-later** (see [`LICENSE`](../LICENSE)). It
bundles the following third-party data and assets under their own terms.

## Natural Earth — map data (public domain)

The default vector map is drawn from Natural Earth data in `worldtime/geodata/`:

- `ne_110m_land.geojson`
- `ne_110m_admin_0_countries.geojson`
- `ne_10m_time_zones.geojson`
- `ne_10m_geographic_lines.geojson`

Natural Earth is in the **public domain**. No permission is needed to use it.
Terms: <https://www.naturalearthdata.com/about/terms-of-use/>

## Tux — default corner logo (Larry Ewing)

`worldtime/assets/tux.png` is Tux, the Linux mascot, created by **Larry Ewing**
(`lewing@isc.tamu.edu`) using **GIMP**.

> Permission to use and/or modify this image is granted provided you acknowledge
> me (`lewing@isc.tamu.edu`) and The GIMP if someone asks.

Source: <https://commons.wikimedia.org/wiki/File:Linux_mascot_tux.png>

## City calibration data — Maxim Proskurnya (GPL)

The city coordinates/offsets used to calibrate the map projection were derived from
Maxim Proskurnya's **GPL** "World Time Wallpaper" (v2.4.x), © 2006–2011
(`axofiber at gmail.com`). See `reference/`.

## Not bundled: IBM/Lenovo ThinkPad artwork

The raster ThinkPad map and the IBM/ThinkPad wordmark are copyright IBM/Lenovo and
are **not** included in this repository. See [`NOTICE`](../NOTICE) for how to supply
your own if you want the `raster` map style or the original logo.

## Development

This project was built with the assistance of AI coding tools.