[cc-devel] License Compatibility Checker using ccREL
vitor at vitorbaptista.com
Wed Oct 6 10:48:00 EDT 2010
I started building the software (now named licc -- License Compatibility
Checker) a few weeks ago. It's begining to take shape, the code is at
http://gitorious.com/vitorbaptista/licc. Suggestions, critiques and patches
I made tests following the compatibility chart at
http://wiki.creativecommons.org/FAQ and it passes them. Also added a few GNU
I found a possible inconsistency between the compatibility chart at
http://wiki.creativecommons.org/FAQ and CC Taiwan's Compatibility Wizard at
http://creativecommons.org.tw/licwiz/english.html. In the first, there's:
> The blank rows for the by-nc-nd and by-nd licenses indicate that derivative
> works or adaptations are not permitted by the license of the original work,
> therefore you are never allowed to re-license them.
But into CC Taiwan consider BY-ND relicensable to BY-NC-ND and BY-ND. Which
one is right?
On Sat, Sep 18, 2010 at 7:24 PM, Vítor Baptista <vitor at vitorbaptista.com>
> Hi Mike,
> On Sat, Sep 18, 2010 at 4:16 PM, Mike Linksvayer <ml at creativecommons.org>
>>> * I'm thinking about how I could, using ccREL, check if two licenses are
>> You can check for incompatibility (but even then an edge case/limited
>> circumstances potential for compatibility could be missed, eg imagine if
>> 1.3 were so modeled; it would appear incompatible with BY-SA, but under
>> circumstances and for a limited time, it was), but can't be certain of
>> compatibility based on CCREL-level permissions/requirements/prohibitions.
>> Licenses could be incompatible for reasons not modeled. For example,
>> 1.0 is not upwards compatible with later versions. (Perhaps this
>> we should add another assertion to the description of BY-SA 1.0 and look
>> other such cases to allow more reasoning with just CCREL level
> Before I found ccREL, I was looking into LIDESC . I prefer ccREL over
> LIDESC's tags because they are more simple, organized, better maintaned
> mainly, because CC and FSF support it. But LIDESC's attributes are more
> specific than ccREL's. It has more than 60 versus ccREL's 12. A license
> could almost be 100% described with LIDESC's tags, but I thought that I
> didn't need this, as my aim is "just" to say "they're not compatible", and
> not "you can distribute but you have to keep Foo's notices in every source
> code, Bar's notices in your About, etc.".
>> It's also important to realize that "compatible" (or "interoperable")
>> often is too imprecise to be useful without specifying up/down,
>> donor/recipient (or whatever your preferred term is); two-way
>> is usually only among very similar licenses, eg among any
>> version/jurisdiction of BY or among jurisdiction ports of a single
>> of BY-SA.
> If I remember well, what I am trying to solve is downwards compatibility.
> use case is "I have a software which is composed by 10 modules, each with
> it's own license. Can I license the whole as GPLv3?". At first, it'll be
> used in OpenGinga, a free implementation of the brazilian's digital tv
>>> At a first glance it seems that I could simply:
>>> 1. You can't give more permissions than those that were given to you
>>> you can give less);
>>> 2. You can't remove prohibitions (but you can add);
>>> 3. You must comply to the requirements of each and every part of your
>>> software (and might add some more);
>>> These seems to work for the simple case (no copyleft/sharealike parts).
>>> But, before I go into that, there're two attributes that I find
>>> 1. High Income Nation Use -- If I don't this permission, what does it
>>> means? That I can't distribute the work in the USA, for example? I
>>> find any licenses that uses this (not CC licenses, at least);
>> Uh oh, you found a bug in our schema -- this is a prohibition developed
>> for the ill-fated http://creativecommons.org/licenses/devnations/2.0/ --
>> glad you couldn't find it. :-) If you find this prohibition, you don't
>> permission to distribute in the USA, for example.
>> Bug: http://code.creativecommons.org/issues/issue663
>> Schema, for those following along described at
>>> 2. Sharing -- Also, couldn't find no licenses using it. It means that I
>>> may create a derivative work and sell it, but can't sell the unmodified
>> Right. Associated with another ill-fated license I'm happy you couldn't
>> find -- http://creativecommons.org/licenses/sampling/1.0/
>> Devnations and sampling received almost no use and were retired 3 years
>> ago, see http://creativecommons.org/weblog/entry/7520 and my
>> mini-celebration http://gondwanaland.com/mlog/2007/06/04/eol/ :-)
> Great! One less thing to confuse me :P
>>> * For compatibility between copyleft licenses, there're x rules:
>>> 1. Is it the same license? If so, they're compatible; if not, use rule
>>> 2. Are they explicitly compatible? For this, I have to use a
>>> pre-calculated database like "GPLv2+ is compatible with GPLv2 or any
>>> version", etc. (maybe it'll be nice to have an extension to ccREL to
>>> this? (Thanks RDF))
>>> If there's a Lesser Copyleft license, my program (as I think of it)
>>> cannot decide, so just tell the user to contact a lawyer. If there's a
>>> ShareAlike, use:
>>> 1. Compatible if it's just a newer version of the license;
>>> 2. Compatible if it's the same version but for a different jurisdiction;
>>> 3. Incompatible if not.
>> Those rules sound right to me, but need a test suite. As above, it might
>> be useful to extend CCREL to support more compatibility reasoning.
> Yes, that's one of the first things that I'll do. Just checking first if I
> am on the right track. I think that  could be used as a first test
> suite... :-)
> Maybe I could find some useful attributes to extend ccREL in LIDESC's list
>  and the license wizard at .
>>> Any thoughts or ideas about this? Does these rules makes sense?
>> Really appreciate that you're doing this work/research! Where can one
>> find your code?
> I still haven't written anything, just some tests of Ruby's RDFa support.
> But, as soon as I begin coding, I'll post a link to my repository here.
> Thanks for your thoughtful comments.
>  http://www.mibsoftware.com/librock/lidesc/tags.htm
>  http://creativecommons.org.tw/licwiz/english.html
>  http://swan.iis.sinica.edu.tw/LicenseWizard/index.htm?en
> Vítor Baptista
> Comissão Organizadora
> IV Encontro de Software Livre da Paraíba
> 6, 7, 8 e 9 de Maio de 2010
> Estação Ciência, Cultura e Artes Cabo Branco
> João Pessoa, PB.
IV Encontro de Software Livre da Paraíba
6, 7, 8 e 9 de Maio de 2010
Estação Ciência, Cultura e Artes Cabo Branco
João Pessoa, PB.
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