Internal Program Version: autoconf-archive  2023.02.20

The GNU Autoconf Archive is a collection of more than 450 macros
for 'GNU Autoconf http://www.gnu.org/software/autoconf`_ that 
have been contributed as free software by friendly supporters of 
the cause from all over the Internet. Every single one of those
macros can be re-used without imposing any restrictions whatsoever
on the licensing of the generated configure script. In particular, 
it is possible to use all those macros in configure scripts that
are meant for non-free software. This policy is unusual for a 
Free Software Foundation project. The FSF firmly believes that 
software ought to be free, and software licenses like the GPL 
are specifically designed to ensure that derivative work based 
on free software must be free as well. In case of Autoconf, 
however, an exception has been made, because Autoconf is at such a
pivotal position in the software development tool chain that the 
benefits from having this tool available as widely as possible 
outweigh the disadvantage that some authors may choose to use it, 
too, for proprietary software.

https://savannah.gnu.org/projects/autoconf-archive