VIM LICENSE
I) There are no restrictions on distributing unmodified copies of Vim except
that they must include this license text. You can also distribute
unmodified parts of Vim, likewise unrestricted except that they must
include this license text. You are also allowed to include executables
that you made from the unmodified Vim sources, plus your own usage
examples and Vim scripts.
II) It is allowed to distribute a modified (or extended) version of Vim,
including executables and/or source code, when the following four
conditions are met:
1) This license text must be included unmodified.
2) The modified Vim must be distributed in one of the following five ways:
a) If you make changes to Vim yourself, you must clearly describe in
the distribution how to contact you. When the maintainer asks you
(in any way) for a copy of the modified Vim you distributed, you
must make your changes, including source code, available to the
maintainer without fee. The maintainer reserves the right to
include your changes in the official version of Vim. What the
maintainer will do with your changes and under what license they
will be distributed is negotiable. If there has been no negotiation
then this license, or a later version, also applies to your changes.
The current maintainer is Bram Moolenaar <Bram@vim.org>. If this
changes it will be announced in appropriate places (most likely
vim.sf.net, www.vim.org and/or comp.editors). When it is completely
impossible to contact the maintainer, the obligation to send him
your changes ceases. Once the maintainer has confirmed that he has
received your changes they will not have to be sent again.
b) If you have received a modified Vim that was distributed as
mentioned under a) you are allowed to further distribute it
unmodified, as mentioned at I). If you make additional changes the
text under a) applies to those changes.
c) Provide all the changes, including source code, with every copy of
the modified Vim you distribute. This may be done in the form of a
context diff. You can choose what license to use for new code you
add. The changes and their license must not restrict others from
making their own changes to the official version of Vim.
d) When you have a modified Vim which includes changes as mentioned
under c), you can distribute it without the source code for the
changes if the following three conditions are met:
- The license that applies to the changes permits you to distribute
the changes to the Vim maintainer without fee or restriction, and
permits the Vim maintainer to include the changes in the official
version of Vim without fee or restriction.
- You keep the changes for at least three years after last
distributing the corresponding modified Vim. When the maintainer
or someone who you distributed the modified Vim to asks you (in
any way) for the changes within this period, you must make them
available to him.
- You clearly describe in the distribution how to contact you. This
contact information must remain valid for at least three years
after last distributing the corresponding modified Vim, or as long
as possible.
e) When the GNU General Public License (GPL) applies to the changes,
you can distribute the modified Vim under the GNU GPL version 2 or
any later version.
3) A message must be added, at least in the output of the ":version"
command and in the intro screen, such that the user of the modified Vim
is able to see that it was modified. When distributing as mentioned
under 2)e) adding the message is only required for as far as this does
not conflict with the license used for the changes.
4) The contact information as required under 2)a) and 2)d) must not be
removed or changed, except that the person himself can make
corrections.
III) If you distribute a modified version of Vim, you are encouraged to use
the Vim license for your changes and make them available to the
maintainer, including the source code. The preferred way to do this is
by e-mail or by uploading the files to a server and e-mailing the URL.
If the number of changes is small (e.g., a modified Makefile) e-mailing a
context diff will do. The e-mail address to be used is
<maintainer@vim.org>
IV) It is not allowed to remove this license from the distribution of the Vim
sources, parts of it or from a modified version. You may use this
license for previous Vim releases instead of the license that they came
with, at your option.