A challenge that faced the Free Software community heavily through out the

early 2000s was the proliferation of incompatible Free Software licenses.  Of

course, we cannot make the GPL compatible with all such licenses. GPLv3

contains provisions that are designed to reduce license incompatibility by

making it easier for developers to combine code carrying non-GPL terms with

GPL'd code.

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\subsection{Additional Permissions}

The GPL is a statement of permissions, some of which have conditions.

Additional terms, terms that supplement those of the GPL, may come to be

placed on, or removed from, GPL-covered code in certain common ways.  We

consider those added terms ``additional permissions'' if they grant

exceptions from the conditions of the GPL, and ``additional requirements'' if

they add conditions to the basic permissions of the GPL. The treatment of

additional permissions and additional requirements under GPLv3 is necessarily

asymmetrical, because they do not raise the same ethical and interpretive

issues; in particular, additional requirements, if allowed without careful

limitation, could transform a GPL'd program into a non-free one.  With these

principles in the background, section 7 answers the following questions: (1)

How do the presence of additional terms on all or part of a GPL'd program