relicensing proposal

[Tom Yu]

I am proposing that we relicense our source code and documentation for
reasons detailed below.  This proposal has received positive feedback
from our sponsors.  Please provide feedback, particularly if you would
adversely affected by this proposal.  I have not yet consulted our
lawyers about this proposal; this is not legal advice; interpretations
are my personal opinions and might not reflect MIT policy, etc.

The essence of the relicensing proposal is:

  * Source code to 3-clause or 2-clause BSD.

  * Documentation to CC-BY-SA-3.0 or CC-BY-3.0.  (maybe including
    Fedora-like modifications; see below)

We would probably implement documentation relicensing first, because
it would be easier, and it would take advantage of our ongoing work of
consolidating documentation into a common format.

In an effort to cut down on license proliferation, and for various
other reasons, I am proposing that we relicense the collective work
that is the MIT krb5 source code as 3-clause or 2-clause BSD.  We
would also relicense individual source code files for which MIT holds
copyright.  The MIT TLO recommends the BSD license as one of its
preferred open source software licenses.  (We are seeking
clarification as to whether they prefer 3-clause or 2-clause.)

We would relicense our documentation under CC-BY-SA 3.0 or CC-BY 3.0.
Some of our existing documentation (the Texinfo-based documentation)
is (somewhat surprisingly) under a strong copyleft, i.e., it requires
that any modified versions only be licensed under exactly the same
terms.  (see the license extract at the end of this message)

I do not know whether there is a strong consensus about applying
copyleft to our documentation (as opposed to the software, where we
have a long history of allowing proprietary derivatives).  One
advantage of using CC-BY-SA instead of the more permissive CC-BY is
that CC-BY-SA would allow us to more easily incorporate content from
resources that are licensed under CC-BY-SA, such as Wikipedia.

There are some concerns that CC-BY-SA 3.0 (and possibly CC-BY 3.0) are
incompatible with the GPL; we may need to do further research about
this issue.  I observe that the Default Content License of the Fedora
Project Contributor Agreement (see URL at end of this message)
consists of CC-BY-SA 3.0 along with a grant of GPL relicensing
permission and a waiver of the CC-BY-SA moral rights clause, perhaps
to forestall this issue.  Does anyone feel that the Fedora approach is
worth the additional complexity that it involves?

The existing license for our collective source code distribution (see
extract at end of this message) has some unusual qualities that have
caused confusion in the past.  For example, some readers have
interpreted the export law warning as a condition of the license,
which they then interpret to be incompatible with the GPL.  I believe
it's important that our software remain unambiguously GPL-compatible,
and applying a "modified" (i.e., sans advertising clause) BSD license
is one way to do that.  Additionally, the license text differs from
most of the variants of the "MIT License" identified as such elsewhere
on the Web.  (It is closest in wording to the license that MIT applied
to other software developed as part of Project Athena, while the
version that most commentators identify as the "MIT License" is closer
to the X Consortium license.

REFERENCES:

License proliferation:
    http://www.opensource.org/proliferation
    http://en.wikipedia.org/wiki/License_proliferation

GPL compatibility:
    http://www.dwheeler.com/essays/gpl-compatible.html

BSD license:
    http://www.opensource.org/licenses/BSD-2-Clause

CC-BY 3.0:
    http://creativecommons.org/licenses/by/3.0/

CC-BY-SA 3.0:
    http://creativecommons.org/licenses/by-sa/3.0/

Fedora Project Contributor Agreement:
    https://fedoraproject.org/wiki/Legal:Fedora_Project_Contributor_Agreement

MIT krb5 license for source code:

    Copyright (C) 1985-2010 by the Massachusetts Institute of
    Technology.

    All rights reserved.

        Export of software employing encryption from the United States
        of America may require a specific license from the United
        States Government.  It is the responsibility of any person or
        organization contemplating export to obtain such a license
        before exporting.

    WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
    distribute this software and its documentation for any purpose and
    without fee is hereby granted, provided that the above copyright
    notice appear in all copies and that both that copyright notice
    and this permission notice appear in supporting documentation, and
    that the name of M.I.T. not be used in advertising or publicity
    pertaining to distribution of the software without specific,
    written prior permission.  Furthermore if you modify this software
    you must label your software as modified software and not
    distribute it in such a fashion that it might be confused with the
    original MIT software.  M.I.T. makes no representations about the
    suitability of this software for any purpose.  It is provided "as
    is" without express or implied warranty.

MIT krb5 license for the Texinfo-format documentation:

    Permission is granted to make and distribute verbatim copies of
    this manual provided the copyright notices and this permission
    notice are preserved on all copies.

    Permission is granted to process this file through TeX and print
    the results, provided the printed document carries a copying
    permission notice identical to this one except for the removal of
    this paragraph (this paragraph not being relevant to the printed
    manual).

    Permission is granted to copy and distribute modified versions of
    this manual under the conditions for verbatim copying, provided
    also that the entire resulting derived work is distributed under
    the terms of a permission notice identical to this one.

    Permission is granted to copy and distribute translations of this
    manual into another language, under the above conditions for
    modified versions.