-@node Library vs. Reusable Code
+@node Library vs Reusable Code
@section Library vs. Reusable Code
Classical libraries are installed as binary object code. Gnulib is
Similarly, Gnulib has a facility for executing a command in a
subprocess. It is at the same time a portability enhancement (it
works on GNU, Unix, and Windows, compared to the classical
-@code{fork()}/@code{exec()} which is not portable to Windows), as well
+@code{fork}/@code{exec} idiom which is not portable to Windows), as well
as an application aid: it takes care of redirecting stdin and/or
stdout if desired, and emits an error message if the subprocess
failed.
@subsection Interfaces to external libraries
Examples are the @samp{iconv} module, which interfaces to the
-@code{iconv()} facility, regardless whether it is contained in libc or in
+@code{iconv} facility, regardless whether it is contained in libc or in
an external @code{libiconv}. Or the @samp{readline} module, which
interfaces to the GNU readline library.
Most modules are under the GPL. Some, mostly modules which can
reasonably be used in libraries, are under LGPL. The source files
always say "GPL", but the real license specification is in the module
-description file.
+description file. If the module description file says "GPL", it means
+"GPLv3+" (GPLv3 or newer, at the licensee's choice); if it says "LGPL",
+it means "LGPLv3+" (LGPLv3 or newer, at the licensee's choice).
+
+More precisely, the license specification in the module description
+file applies to the files in @file{lib/} and @file{build-aux/}. Different
+licenses apply to files in special directories:
+
+@table @file
+@item modules/
+Module description files are under this copyright:
+
+@quotation
+Copyright @copyright{} 200X-200Y Free Software Foundation, Inc.@*
+Copying and distribution of this file, with or without modification,
+in any medium, are permitted without royalty provided the copyright
+notice and this notice are preserved.
+@end quotation
+
+@item m4/
+Autoconf macro files are under this copyright:
+
+@quotation
+Copyright @copyright{} 200X-200Y Free Software Foundation, Inc.@*
+This file is free software; the Free Software Foundation
+gives unlimited permission to copy and/or distribute it,
+with or without modifications, as long as this notice is preserved.
+@end quotation
+
+@item tests/
+If a license statement is not present in a test module, the test files are
+under GPL. Even if the corresponding source module is under LGPL, this is
+not a problem, since compiled tests are not installed by ``make install''.
+
+@item doc/
+Documentation files are under this copyright:
+
+@quotation
+Copyright @copyright{} 2004-2008 Free Software Foundation, Inc.@*
+Permission is granted to copy, distribute and/or modify this document
+under the terms of the GNU Free Documentation License, Version 1.3 or
+any later version published by the Free Software Foundation; with no
+Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A
+copy of the license is included in the section entitled ``GNU Free
+Documentation License''.
+@end quotation
+@end table
If you want to use some Gnulib modules under LGPL, you can do so by
passing the option @samp{--lgpl} to @code{gnulib-tool}. This will
replace the GPL header with an LGPL header while copying the source
-files to your package.
+files to your package. Similarly, if you want some Gnulib modules
+under LGPLv2+ (Lesser GPL version 2.1 or newer), you can do so by
+passing the option @samp{--lgpl=2} to @code{gnulib-tool}.
Keep in mind that when you submit patches to files in Gnulib, you should
license them under a compatible license. This means that sometimes the
Gnulib modules are continually adapted, to match new practices, to be
consistent with newly added modules, or simply as a response to build
failure reports. We don't make releases, but instead recommend to use the
-newest version of Gnulib from the CVS, except in periods of major changes.
+newest version of Gnulib from the Git repository, except in periods of major
+changes. The source tree can also be fetched from a read-only CVS that
+mirrors the Git repository.
@node Openness
@section Openness