modified versions to be distributed under the GPL\@.  Second, the GPL states

that no further restrictions may be placed on the rights of recipients.

Third, all other software freedom respecting licenses in common use contain certain

requirements, many of which are not conditions made by the GPL\@.  Thus, when

GPL'd code is modified by combination with code covered by another formal

license that specifies other requirements, and that modified code is then

distributed to others, the freedom of recipients may be burdened by

additional requirements in violation of the GPL.  It can be seen that

additional permissions in other licenses do not raise any problems of license

compatibility.

GPLv3  took a new approach to the issue of combining GPL'd code with

code governed by the terms of other software freedom licenses.  Traditional

GPLv2 license compatibility theory (which was not explicitly stated in GPLv2

itself, but treated as a license interpretation matter by the FSF) held that GPLv2 allowed such

combinations only if the non-GPL licensing terms permitted distribution under

the GPL and imposed no restrictions on the code that were not also imposed by

the GPL\@.  In practice, the FSF historically supplemented that policy with a structure of

exceptions for certain kinds of combinations.

GPLv3~\S7  implements a more explicit policy on license

compatibility.  It formalizes the circumstances under which a licensee may

release a covered work that includes an added part carrying non-GPL terms. 

GPLv3~\S7 distinguish between terms that provide additional permissions, and terms that

place additional requirements on the code, relative to the permissions and

requirements established by applying the GPL to the code.

As discussed in the previous section of this tutorial, GPLv3~\S7 first and foremost explicitly allows added parts covered by terms with

additional permissions to be combined with GPL'd code. This codifies the

existing practice of regarding such licensing terms as compatible with the

GPL\@. A downstream user of a combined GPL'd work who modifies such an added

part may remove the additional permissions, in which case the broader

permissions no longer apply to the modified version, and only the terms of

the GPL apply to it.

In its treatment of terms that impose additional requirements, GPLv3\S7

extends the range of licensing terms with which the GPL is compatible.  An

added part carrying additional requirements may be combined with GPL'd code,

but only if those requirements belong to an set enumerated in GPLv3\S7. There

are, of course,  limits on the acceptable additional requirements, which to

ensures that enhanced license compatibility does not

defeat the broader software-freedom-defending terms of the GPL\@. Unlike terms that grant

additional permissions, terms that impose additional requirements cannot be

removed by a downstream user of the combined GPL'd work, because only in the

pathological case\footnote{Theoretically, a user could collect copyright

  assignment from all known contributors and then do this, but this would

  indeed be the pathological case.}  would a user have the right to do so.

% FIXME:  removing additional restrictions

% FIXME:  probably mostly still right, needs some updates, though.

Section 7 requires a downstream user of a covered work to preserve the

non-GPL terms covering the added parts just as they must preserve the GPL, as

long as any substantial portion of those parts is present in the user's

version.

% FIXME: minor rewrites needed

Section 7 points out that GPLv3 itself makes no assertion that an additional

requirement is enforceable by the copyright holder.  However, section 7 makes

clear that enforcement of such requirements is expected to be by the

termination procedure given in section 8 of GPLv3.

% FIXME: better context, etc.

Some have questioned whether section 7 is needed, and some have suggested

that it creates complexity that did not previously exist.  We point out to

those readers that there is already GPLv2-licensed code that carries

additional terms.  One of the objectives of section 7 is to rationalize

existing practices of program authors and modifiers by setting clear

guidelines regarding the removal and addition of such terms.  With its

carefully limited list of allowed additional requirements, section 7

accomplishes additional objectives, permitting the expansion of the base of

code available for GPL developers, while also encouraging useful

experimentation with requirements we do not include in the GPL itself.

\section{GPLv3~\S8: A Lighter Termination}

% FIXME:  probably mostly still right, needs some updates, though.

GPLv2 provided for automatic termination of the rights of a person who

copied, modified, sublicensed, or distributed a work in violation of the

license.  Automatic termination can be too harsh for those who have committed

an inadvertent violation, particularly in cases involving distribution of

large collections of software having numerous copyright holders.  A violator

who resumes compliance with GPLv2 would need to obtain forgiveness from all

copyright holders, but even to contact them all might be impossible.

% FIXME: needs to be updated to describe more complex termination

Section 8 of GPLv3 replaces automatic termination with a non-automatic

termination process.  Any copyright holder for the licensed work may opt to

terminate the rights of a violator of the license, provided that the

copyright holder has first given notice of the violation within 60 days of