As a distribution, this software is effectively licensed under the GNU
General Public License as published by the Free Software foundation;
either version 3 of the License, or (at your option) any later version
("GPL").  The full text of this license is in the file `COPYING.GPL3`.

However, most of it is actually licensed under the GNU Lesser General
Public License as published by the Free Software foundation; either
version 2.1 of the License, or (at your option) any later version
("LGPL").  The full text of this license is in the file
`COPYING.LGPL21`.

That is: When creating a derivative piece of software, if you remove
the GPL parts, you are free to use the remaining source under the
terms of the LGPL.