The R package cdtr is released under the MIT license (see the LICENSE file).

It bundles the following third-party source code under src/CDT/:

1. The 'CDT' C++ library (CDT.h, CDT.hpp, CDTUtils.h, CDTUtils.hpp, KDTree.h,
   LocatorKDTree.h, Triangulation.h, Triangulation.hpp, portable_nth_element.hpp,
   remove_at.hpp).
   Source: https://github.com/artem-ogre/CDT
   Copyright (c) 2019 Leica Geosystems Technology AB
   Copyright (c) The CDT Contributors
   Licensed under the Mozilla Public License, v. 2.0 (full text in
   inst/LICENSE.CDT).

   Local modification: in Triangulation.h the '#pragma GCC diagnostic'
   push/ignored/pop around the ICallbackHandler interface was removed, and the
   unused parameter names of its default (empty) methods are kept as comments
   instead, so the header compiles without -Wunused-parameter warnings and
   passes R CMD check's test for pragmas suppressing diagnostics. The class is
   only compiled when CDT_ENABLE_CALLBACK_HANDLER is defined, which cdtr does
   not do. No other changes to the upstream sources.

2. Robust geometric predicates (predicates.h).
   Copyright (c) 2019 William C. Lenthe
   Licensed under a 3-clause BSD license (full text in the file header).