com/options/license/LGPL-2.1-or-later

GNU LESSER GENERAL PUBLIC LICENSE

Version 2.1, February 1999

Copyright (C) 1991, 1999 Free Software Foundation, Inc.

51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

Everyone is permitted to copy and distribute verbatim copies of this license
document, but changing it is not allowed.

[This is the first released version of the Lesser GPL. It also counts as the
successor of the GNU Library Public License, version 2, hence the version
number 2.1.]

Preamble

The licenses for most software are designed to take away your freedom to share
and change it. By contrast, the GNU General Public Licenses are intended to
guarantee your freedom to share and change free software--to make sure the
software is free for all its users.

This license, the Lesser General Public License, applies to some specially
designated software packages--typically libraries--of the Free Software Foundation
and other authors who decide to use it. You can use it too, but we suggest
you first think carefully about whether this license or the ordinary General
Public License is the better strategy to use in any particular case, based
on the explanations below.

When we speak of free software, we are referring to freedom of use, not price.
Our General Public Licenses are designed to make sure that you have the freedom
to distribute copies of free software (and charge for this service if you
wish); that you receive source code or can get it if you want it; that you
can change the software and use pieces of it in new free programs; and that
you are informed that you can do these things.

To protect your rights, we need to make restrictions that forbid distributors
to deny you these rights or to ask you to surrender these rights. These restrictions
translate to certain responsibilities for you if you distribute copies of
the library or if you modify it.

For example, if you distribute copies of the library, whether gratis or for
a fee, you must give the recipients all the rights that we gave you. You must
make sure that they, too, receive or can get the source code. If you link
other code with the library, you must provide complete object files to the
recipients, so that they can relink them with the library after making changes
to the library and recompiling it. And you must show them these terms so they
know their rights.

We protect your rights with a two-step method: (1) we copyright the library,
and (2) we offer you this license, which gives you legal permission to copy,
distribute and/or modify the library.

To protect each distributor, we want to make it very clear that there is no
warranty for the free library. Also, if the library is modified by someone
else and passed on, the recipients should know that what they have is not
the original version, so that the original author's reputation will not be
affected by problems that might be introduced by others.

Finally, software patents pose a constant threat to the existence of any free
program. We wish to make sure that a company cannot effectively restrict the
users of a free program by obtaining a restrictive license from a patent holder.
Therefore, we insist that any patent license obtained for a version of the
library must be consistent with the full freedom of use specified in this
license.

Most GNU software, including some libraries, is covered by the ordinary GNU
General Public License. This license, the GNU Lesser General Public License,
applies to certain designated libraries, and is quite different from the ordinary
General Public License. We use this license for certain libraries in order
to permit linking those libraries into non-free programs.

When a program is linked with a library, whether statically or using a shared
library, the combination of the two is legally speaking a combined work, a
derivative of the original library. The ordinary General Public License therefore
permits such linking only if the entire combination fits its criteria of freedom.
The Lesser General Public License permits more lax criteria for linking other
code with the library.

We call this license the "Lesser" General Public License because it does Less
to protect the user's freedom than the ordinary General Public License. It
also provides other free software developers Less of an advantage over competing
non-free programs. These disadvantages are the reason we use the ordinary
General Public License for many libraries. However, the Lesser license provides
advantages in certain special circumstances.

For example, on rare occasions, there may be a special need to encourage the
widest possible use of a certain library, so that it becomes a de-facto standard.
To achieve this, non-free programs must be allowed to use the library. A more
frequent case is that a free library does the same job as widely used non-free
libraries. In this case, there is little to gain by limiting the free library
to free software only, so we use the Lesser General Public License.

In other cases, permission to use a particular library in non-free programs
enables a greater number of people to use a large body of free software. For
example, permission to use the GNU C Library in non-free programs enables
many more people to use the whole GNU operating system, as well as its variant,
the GNU/Linux operating system.

Although the Lesser General Public License is Less protective of the users'
freedom, it does ensure that the user of a program that is linked with the
Library has the freedom and the wherewithal to run that program using a modified
version of the Library.

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, whereas the latter must be combined with the library in
order to run.

TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION

0. This License Agreement applies to any software library or other program
which contains a notice placed by the copyright holder or other authorized
party saying it may be distributed under the terms of this Lesser General
Public License (also called "this License"). Each licensee is addressed as
"you".

A "library" means a collection of software functions and/or data prepared
so as to be conveniently linked with application programs (which use some
of those functions and data) to form executables.

The "Library", below, refers to any such software library or work which has
been distributed under these terms. A "work based on the Library" means either
the Library or any derivative work under copyright law: that is to say, a
work containing the Library or a portion of it, either verbatim or with modifications
and/or translated straightforwardly into another language. (Hereinafter, translation
is included without limitation in the term "modification".)

"Source code" for a work means the preferred form of the work for making modifications
to it. For a library, complete source code means all the source code for all
modules it contains, plus any associated interface definition files, plus
the scripts used to control compilation and installation of the library.

Activities other than copying, distribution and modification are not covered
by this License; they are outside its scope. The act of running a program
using the Library is not restricted, and output from such a program is covered
only if its contents constitute a work based on the Library (independent of
the use of the Library in a tool for writing it). Whether that is true depends
on what the Library does and what the program that uses the Library does.

1. You may copy and distribute verbatim copies of the Library's complete source
code as you receive it, in any medium, provided that you conspicuously and
appropriately publish on each copy an appropriate copyright notice and disclaimer
of warranty; keep intact all the notices that refer to this License and to
the absence of any warranty; and distribute a copy of this License along with
the Library.

You may charge a fee for the physical act of transferring a copy, and you
may at your option offer warranty protection in exchange for a fee.

2. You may modify your copy or copies of the Library or any portion of it,
thus forming a work based on the Library, and copy and distribute such modifications
or work under the terms of Section 1 above, provided that you also meet all
of these conditions:

      a) The modified work must itself be a software library.

b) You must cause the files modified to carry prominent notices stating that
you changed the files and the date of any change.

c) You must cause the whole of the work to be licensed at no charge to all
third parties under the terms of this License.

d) If a facility in the modified Library refers to a function or a table of
data to be supplied by an application program that uses the facility, other
than as an argument passed when the facility is invoked, then you must make
a good faith effort to ensure that, in the event an application does not supply
such function or table, the facility still operates, and performs whatever
part of its purpose remains meaningful.

(For example, a function in a library to compute square roots has a purpose
that is entirely well-defined independent of the application. Therefore, Subsection
2d requires that any application-supplied function or table used by this function
must be optional: if the application does not supply it, the square root function
must still compute square roots.)

These requirements apply to the modified work as a whole. If identifiable
sections of that work are not derived from the Library, and can be reasonably
considered independent and separate works in themselves, then this License,
and its terms, do not apply to those sections when you distribute them as
separate works. But when you distribute the same sections as part of a whole
which is a work based on the Library, the distribution of the whole must be
on the terms of this License, whose permissions for other licensees extend
to the entire whole, and thus to each and every part regardless of who wrote
it.

Thus, it is not the intent of this section to claim rights or contest your
rights to work written entirely by you; rather, the intent is to exercise
the right to control the distribution of derivative or collective works based
on the Library.

In addition, mere aggregation of another work not based on the Library with
the Library (or with a work based on the Library) on a volume of a storage
or distribution medium does not bring the other work under the scope of this
License.

3. You may opt to apply the terms of the ordinary GNU General Public License
instead of this License to a given copy of the Library. To do this, you must
alter all the notices that refer to this License, so that they refer to the
ordinary GNU General Public License, version 2, instead of to this License.
(If a newer version than version 2 of the ordinary GNU General Public License
has appeared, then you can specify that version instead if you wish.) Do not
make any other change in these notices.

Once this change is made in a given copy, it is irreversible for that copy,
so the ordinary GNU General Public License applies to all subsequent copies
and derivative works made from that copy.

This option is useful when you wish to copy part of the code of the Library
into a program that is not a library.

4. You may copy and distribute the Library (or a portion or derivative of
it, under Section 2) in object code or executable form under the terms of
Sections 1 and 2 above provided that you accompany it with the complete corresponding
machine-readable source code, which must be distributed under the terms of
Sections 1 and 2 above on a medium customarily used for software interchange.

If distribution of object code is made by offering access to copy from a designated
place, then offering equivalent access to copy the source code from the same
place satisfies the requirement to distribute the source code, even though
third parties are not compelled to copy the source along with the object code.

5. A program that contains no derivative of any portion of the Library, but
is designed to work with the Library by being compiled or linked with it,
is called a "work that uses the Library". Such a work, in isolation, is not
a derivative work of the Library, and therefore falls outside the scope of
this License.

However, linking a "work that uses the Library" with the Library creates an
executable that is a derivative of the Library (because it contains portions
of the Library), rather than a "work that uses the library". The executable
is therefore covered by this License. Section 6 states terms for distribution
of such executables.

When a "work that uses the Library" uses material from a header file that
is part of the Library, the object code for the work may be a derivative work
of the Library even though the source code is not. Whether this is true is
especially significant if the work can be linked without the Library, or if
the work is itself a library. The threshold for this to be true is not precisely
defined by law.

If such an object file uses only numerical parameters, data structure layouts
and accessors, and small macros and small inline functions (ten lines or less
in length), then the use of the object file is unrestricted, regardless of
whether it is legally a derivative work. (Executables containing this object
code plus portions of the Library will still fall under Section 6.)

Otherwise, if the work is a derivative of the Library, you may distribute
the object code for the work under the terms of Section 6. Any executables
containing that work also fall under Section 6, whether or not they are linked
directly with the Library itself.

6. As an exception to the Sections above, you may also combine or link a "work
that uses the Library" with the Library to produce a work containing portions
of the Library, and distribute that work under terms of your choice, provided
that the terms permit modification of the work for the customer's own use
and reverse engineering for debugging such modifications.

You must give prominent notice with each copy of the work that the Library
is used in it and that the Library and its use are covered by this License.
You must supply a copy of this License. If the work during execution displays
copyright notices, you must include the copyright notice for the Library among
them, as well as a reference directing the user to the copy of this License.
Also, you must do one of these things:

a) Accompany the work with the complete corresponding machine-readable source
code for the Library including whatever changes were used in the work (which
must be distributed under Sections 1 and 2 above); and, if the work is an
executable linked with the Library, with the complete machine-readable "work
that uses the Library", as object code and/or source code, so that the user
can modify the Library and then relink to produce a modified executable containing
the modified Library. (It is understood that the user who changes the contents
of definitions files in the Library will not necessarily be able to recompile
the application to use the modified definitions.)

b) Use a suitable shared library mechanism for linking with the Library. A
suitable mechanism is one that (1) uses at run time a copy of the library
already present on the user's computer system, rather than copying library
functions into the executable, and (2) will operate properly with a modified
version of the library, if the user installs one, as long as the modified
version is interface-compatible with the version that the work was made with.

c) Accompany the work with a written offer, valid for at least three years,
to give the same user the materials specified in Subsection 6a, above, for
a charge no more than the cost of performing this distribution.

d) If distribution of the work is made by offering access to copy from a designated
place, offer equivalent access to copy the above specified materials from
the same place.

e) Verify that the user has already received a copy of these materials or
that you have already sent this user a copy.

For an executable, the required form of the "work that uses the Library" must
include any data and utility programs needed for reproducing the executable
from it. However, as a special exception, the materials to be distributed
need not include anything that is normally distributed (in either source or
binary form) with the major components (compiler, kernel, and so on) of the
operating system on which the executable runs, unless that component itself
accompanies the executable.

It may happen that this requirement contradicts the license restrictions of
other proprietary libraries that do not normally accompany the operating system.
Such a contradiction means you cannot use both them and the Library together
in an executable that you distribute.

7. You may place library facilities that are a work based on the Library side-by-side
in a single library together with other library facilities not covered by
this License, and distribute such a combined library, provided that the separate
distribution of the work based on the Library and of the other library facilities
is otherwise permitted, and provided that you do these two things:

a) Accompany the combined library with a copy of the same work based on the
Library, uncombined with any other library facilities. This must be distributed
under the terms of the Sections above.

b) Give prominent notice with the combined library of the fact that part of
it is a work based on the Library, and explaining where to find the accompanying
uncombined form of the same work.

8. You may not copy, modify, sublicense, link with, or distribute the Library
except as expressly provided under this License. Any attempt otherwise to
copy, modify, sublicense, link with, or distribute the Library is void, and
will automatically terminate your rights under this License. However, parties
who have received copies, or rights, from you under this License will not
have their licenses terminated so long as such parties remain in full compliance.

9. You are not required to accept this License, since you have not signed
it. However, nothing else grants you permission to modify or distribute the
Library or its derivative works. These actions are prohibited by law if you
do not accept this License. Therefore, by modifying or distributing the Library
(or any work based on the Library), you indicate your acceptance of this License
to do so, and all its terms and conditions for copying, distributing or modifying
the Library or works based on it.

10. Each time you redistribute the Library (or any work based on the Library),
the recipient automatically receives a license from the original licensor
to copy, distribute, link with or modify the Library subject to these terms
and conditions. You may not impose any further restrictions on the recipients'
exercise of the rights granted herein. You are not responsible for enforcing
compliance by third parties with this License.

11. If, as a consequence of a court judgment or allegation of patent infringement
or for any other reason (not limited to patent issues), conditions are imposed
on you (whether by court order, agreement or otherwise) that contradict the
conditions of this License, they do not excuse you from the conditions of
this License. If you cannot distribute so as to satisfy simultaneously your
obligations under this License and any other pertinent obligations, then as
a consequence you may not distribute the Library at all. For example, if a
patent license would not permit royalty-free redistribution of the Library
by all those who receive copies directly or indirectly through you, then the
only way you could satisfy both it and this License would be to refrain entirely
from distribution of the Library.

If any portion of this section is held invalid or unenforceable under any
particular circumstance, the balance of the section is intended to apply,
and the section as a whole is intended to apply in other circumstances.

It is not the purpose of this section to induce you to infringe any patents
or other property right claims or to contest validity of any such claims;
this section has the sole purpose of protecting the integrity of the free
software distribution system which is implemented by public license practices.
Many people have made generous contributions to the wide range of software
distributed through that system in reliance on consistent application of that
system; it is up to the author/donor to decide if he or she is willing to
distribute software through any other system and a licensee cannot impose
that choice.

This section is intended to make thoroughly clear what is believed to be a
consequence of the rest of this License.

12. If the distribution and/or use of the Library is restricted in certain
countries either by patents or by copyrighted interfaces, the original copyright
holder who places the Library under this License may add an explicit geographical
distribution limitation excluding those countries, so that distribution is
permitted only in or among countries not thus excluded. In such case, this
License incorporates the limitation as if written in the body of this License.

13. The Free Software Foundation may publish revised and/or new versions of
the Lesser General Public License from time to time. Such new versions will
be similar in spirit to the present version, but may differ in detail to address
new problems or concerns.

Each version is given a distinguishing version number. If the Library specifies
a version number of this License which applies to it and "any later version",
you have the option of following the terms and conditions either of that version
or of any later version published by the Free Software Foundation. If the
Library does not specify a license version number, you may choose any version
ever published by the Free Software Foundation.

14. If you wish to incorporate parts of the Library into other free programs
whose distribution conditions are incompatible with these, write to the author
to ask for permission. For software which is copyrighted by the Free Software
Foundation, write to the Free Software Foundation; we sometimes make exceptions
for this. Our decision will be guided by the two goals of preserving the free
status of all derivatives of our free software and of promoting the sharing
and reuse of software generally.

   NO WARRANTY

15. BECAUSE THE LIBRARY IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY FOR
THE LIBRARY, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN OTHERWISE
STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE LIBRARY
"AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING,
BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE
OF THE LIBRARY IS WITH YOU. SHOULD THE LIBRARY PROVE DEFECTIVE, YOU ASSUME
THE COST OF ALL NECESSARY SERVICING, REPAIR OR CORRECTION.

16. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR REDISTRIBUTE
THE LIBRARY AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY
GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE
OR INABILITY TO USE THE LIBRARY (INCLUDING BUT NOT LIMITED TO LOSS OF DATA
OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES
OR A FAILURE OF THE LIBRARY TO OPERATE WITH ANY OTHER SOFTWARE), EVEN IF SUCH
HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
END OF TERMS AND CONDITIONS

How to Apply These Terms to Your New Libraries

If you develop a new library, and you want it to be of the greatest possible
use to the public, we recommend making it free software that everyone can
redistribute and change. You can do so by permitting redistribution under
these terms (or, alternatively, under the terms of the ordinary General Public
License).

To apply these terms, attach the following notices to the library. It is safest
to attach them to the start of each source file to most effectively convey
the exclusion of warranty; and each file should have at least the "copyright"
line and a pointer to where the full notice is found.

<one line to give the library's name and an idea of what it does.>

Copyright (C) <year> <name of author>

This library is free software; you can redistribute it and/or modify it under
the terms of 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.

This library is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
details.

You should have received a copy of the GNU Lesser General Public License along
with this library; if not, write to the Free Software Foundation, Inc., 51
Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

Also add information on how to contact you by electronic and paper mail.

You should also get your employer (if you work as a programmer) or your school,
if any, to sign a "copyright disclaimer" for the library, if necessary. Here
is a sample; alter the names:

Yoyodyne, Inc., hereby disclaims all copyright interest in

the library `Frob' (a library for tweaking knobs) written

by James Random Hacker.

< signature of Ty Coon > , 1 April 1990

Ty Coon, President of Vice

That's all there is to it!