Copyleft variation of MIT license
Hello,
I had been using the GPL for some years without fully understanding
its implications. Recently, I spent some time thinking about my
ethical beliefs regarding free software and discovered that I prefer
something like Creative Commons' by-sa (attribution + share-alike)
license. That is, I want the source code of my software to remain
free, like a free bird that cannot be caged.
Because CC does not recommend using their licenses for software, my
friend suggested the SleepyCat license[1]. However, I found its
copyleft condition (the third condition) to be wordy and confusing.
I looked at other by-sa licenses (particularly MPL, CDDL, CPL, EPL)
but found them to be lengthy. Instead, I admire the MIT license for
its short length and comprehensibility, and wish to make a copyleft
variation of the MIT license[2].
The MIT license has the following properties (from Ed Burnette's
survey[3] of free software licenses):
1. Code is protected by copyright? Yes
2. Code can be used in closed source projects? Yes
3. Program that uses (incorporates) the software can be sold
commercially? Yes
4. Source to bug fixes and modifications must be released? No
5. Provides explicit patent license? No
I tried to modify the conditions paragraph of the MIT license so
that question 4 (shown above) is given a "Yes" answer. Here are my
variations:
(a) The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.
These copies and portions shall be distributed in source code form.
(b) The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.
These copies and portions, if modified, shall be distributed in
source code form.
(c) The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.
These copies and portions, if modified, shall be distributed with
modifications in source code form.
Variation (a) tries to say that if you use source code (regardless
of whether you modified it) that was copied from the Software, then
you must distribute those copied parts (as source code) along with
your derivative work.
Variation (b) applies the stuff in (a) only if you make
modifications to code you copied from the Software.
Variation (c) tries to prevent you from copying code from the
Software, modifying it, and keeping the modifications secret.
Are these variations flawed? How can I improve them?
Thanks for your consideration.
[1] http://www.opensource.org/licenses/sleepycat.php
[2] http://www.opensource.org/licenses/mit-license.php
[3] http://blogs.zdnet.com/Burnette/?p=131
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