\end{enumerate}

Additional permissions present the easier case.  Since the mid-1990s,

permissive exceptions often appeared alongside GPLv2 with permissive

exceptions to allow combination

with certain non-free code.  Typically, downstream

stream recipients could remove those exceptions and operate under pure GPLv2.

Similarly, LGPLv2.1 is in essence a permissive variant of GPLv2,

and it permits relicensing under the GPL\@.  

\sectin

These practices are now generalized via GPLv3~\S7.

A licensee may remove any additional permission from

a covered work, whether it was placed by the original author or by an

upstream distributor.  A licensee may also add any kind of additional

permission to any part of a work for which the licensee has, or can give,

appropriate copyright permission. For example, if the licensee has written

that part, the licensee is the copyright holder for that part and can

therefore give additional permissions that are applicable to it.

Alternatively, the part may have been written by someone else and licensed,

with the additional permissions, to that licensee.  Any additional

permissions on that part are, in turn, removable by downstream recipients.

As GPLv3~\S7\P1 explains, the effect of an additional permission depends on

whether the permission applies to the whole work or a part.

% FIXME-LATER: LGPLv3 will have its own section

Indeed, LGPLv3 is itself simply  a list of additional permissions supplementing the

terms of GPLv3.  GPLv3\S7 has thus provided the basis for recasting a

formally complex license as an elegant set of added terms, without changing

any of the fundamental features of the existing LGPL\@.  LGPLv3 is thus  a model for developers wishing to license their works under the

GPL with permissive exceptions.  The removability of additional permissions

under GPLv3\S7 does not alter any existing behavior of the LGPL since the LGPL

has always allowed relicensing under the ordinary GPL\@.

\section{GPLv3~\S7: Understanding License Compatibility}

\label{license-compatibility}

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

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

course, the GPL cannot possibly be compatible with all such licenses.

However, 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.

This license compatibility issue arises for

three reasons.  First, the GPL is a strong copyleft license, requiring

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

its most recent occurrence. A violator who has been given notice may make

efforts to enter into compliance and may request that the copyright holder

agree not exercise the right of termination; the copyright holder may choose

to grant or refuse this request.

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

If a licensee who is in violation of GPLv3 acts to correct the violation and

enter into compliance, and the licensee receives no notice of the past

violation within 60 days, then the licensee need not worry about termination

of rights under the license.

In Draft 3 the termination provision of section 8 has been revised to

indicate that, if a licensee violates the GPL, a contributor may terminate

any patent licenses that it granted under the first paragraph of section 11

to that licensee, in addition to any copyright permissions the contributor

granted to the licensee.  Therefore, a contributor may terminate the patent

licenses it granted to a downstream licensee who brings patent infringement

litigation in violation of section 10.

We have made two substantive changes to section 8.  First, we have clarified

that patent rights granted under the GPL are among the rights that a

copyright holder may terminate under section 8.  Therefore, a contributor who

grants a patent license under the first paragraph of section 11 may terminate

that patent license, just as that contributor may terminate copyright rights,

to a downstream recipient who has violated the license.  We think that this

is a reasonable result, and was already implicit in the wording of the

termination provision in our earlier drafts.  Moreover, this clarification

should encourage patent holders to make contributions to GPL-covered

programs.

Second, we have modified the termination procedure by providing a limited

opportunity to cure license violations, an improvement that was requested by

many different members of our community.  If a licensee has committed a

first-time violation of the GPL with respect to a given copyright holder, but

the licensee cures the violation within 30 days following receipt of notice

of the violation, then any of the licensee's GPL rights that have been

terminated by the copyright holder are ``automatically reinstated.''  The

addition of the cure opportunity achieves a better balance than our earlier

section 8 drafts between facilitating enforcement of the license and

protecting inadvertent violators against unfair results.

We have restructured the form of section 8 by replacing non-automatic

termination with automatic termination coupled with opportunities for

provisional and permanent reinstatement of rights.  The revised wording does

not alter the underlying policy or details of procedure established in the

previous drafts, including the 60-day period of repose and 30-day cure

opportunity for first-time violators.  The restoration of automatic