Data license for the grid files bundled with and distributed alongside
landmetrics (distance_to_land_*.nc, land_fraction_*.nc).

These files are derived from GSHHG (Global Self-consistent, Hierarchical,
High-resolution Geography):

    Wessel, P., and W. H. F. Smith (1996), A global, self-consistent,
    hierarchical, high-resolution shoreline database, J. Geophys. Res.,
    101(B4), 8741-8743, doi:10.1029/96JB00104.
    https://www.soest.hawaii.edu/pwessel/gshhg/

GSHHG is released under the GNU Lesser General Public License (LGPL). This
derived dataset -- a rasterized distance/fraction grid computed from GSHHG's
coastline polygons -- is redistributed under the GNU Lesser General Public
License, version 3 or later (LGPL-3.0-or-later):

    https://www.gnu.org/licenses/lgpl-3.0.html

A complete, reproducible description of how these grids were derived from
the source GSHHG polygons -- coastline levels used, the nearest-coastline
distance method, the land-fraction estimation method, and the file schema
itself -- is given in docs/grid_format.md. The code that queries these grids
(this package) is source-available under the MIT license (see LICENSE); the
grid *generation* code that produced these specific files is not published,
but the method is fully described so an equivalent derivation could be
reproduced independently from the same public GSHHG source data.
