ZyXEL Communications MWR222 - V1.0 Manual page 309

individually obtain patent licenses, thus in effect transforming the program
into proprietary software. To prevent this, we have made it clear that any
patent must be licensed for everyone's free use or not licensed at all.
Most GNU software, including some libraries, is covered by the ordinary
GNU General Public License, which was designed for utility programs. This
license, the GNU Library General Public License, applies to certain
designated libraries. This license is quite different from the ordinary one;
be sure to read it in full, and don't assume that anything in it is the same
as in the ordinary license.
The reason we have a separate public license for some libraries is that
they blur the distinction we usually make between modifying or adding to
a program and simply using it. Linking a program with a library, without
changing the library, is in some sense simply using the library, and is
analogous to running a utility program or application program. However,
in a textual and legal sense, the linked executable is a combined work, a
derivative of the original library, and the ordinary General Public License
treats it as such.
Because of this blurred distinction, using the ordinary General Public
License for libraries did not effectively promote software sharing, because
most developers did not use the libraries. We concluded that weaker
conditions might promote sharing better.
However, unrestricted linking of non-free programs would deprive the
users of those programs of all benefit from the free status of the libraries
themselves. This Library General Public License is intended to permit
developers of non-free programs to use free libraries, while preserving
your freedom as a user of such programs to change the free libraries that
are incorporated in them. (We have not seen how to achieve this as
regards changes in header files, but we have achieved it as regards
changes in the actual functions of the Library.) The hope is that this will
lead to faster development of free libraries.
The precise terms and conditions for copying, distribution and modification
follow. Pay close attention to the difference between a "work based on the
library" and a "work that uses the library". The former contains code
derived from the library, while the latter only works together with the
library.
Note that it is possible for a library to be covered by the ordinary General
Public License rather than by this special one.
MWR222 User's Guide
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