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Licensing a work using a GPL-ed library under the LGPL


The matrix under


says that a work using a GPL-ed library can be licensed under the LGPL "if you convert to GPL". For example the KDE libraries which use the GPL-ed Qt libraries are themselves licensed under the LGPL.

But I don't understand what is the meaning of licensing something under the LGPL if it is effectively under the GPL anyway because it uses a GPL-ed library. So what is the point in licensing it under the LGPL?

Could it be that parts of such a work which do not use a GPL-ed library can be used under the LGPL? Is there such a legal distinction between "parts that use the GPL-ed library" and "parts that don't"?

A related question is about the people who have contributed code to Qt under BSD/MIT-style licenses (see http://doc.trolltech.com/4.3/licenses.html). They have definitely used Qt's own classes in their own code. I also don't think that all of them would have got a commercial Qt license which gives them the right to license their code in whatever way they wish.

In that case, how can their code which uses GPL-ed Qt be licensed under anything other than the GPL? Is it that the copyright owner of Qt has granted them special permission to license their code under those free non-copyleft licenses? If so, isn't it necessary for legal propriety to mention that in that page?


Shriramana Sharma.

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