server.  Subsection 6d clarifies that the distributor must offer equivalent

access to copy the source code ``in the same way through the same place.''

This wording permits a distributor to offer a third party access to both

object code and source code on a single network portal or web page, even

though the access may include links to different physical servers.  For

example, a downstream distributor may provide a link to an upstream

distributor's server and arrange with the operator of that server to keep the

source code available for copying for as long as the downstream distributor

enables access to the object code.  This codifies what has been our

interpretation of GPLv2.

%FIXME: 6e, peer-to-peer

%  FIXME: Not final paragraph anymore. 

The final paragraph of section 6 takes account of the fact that the Complete

Corresponding Source Code may include added parts that carry non-GPL terms,

as permitted by section 7.

% FIXME: update lock-down section to work with more recent drafts

Though the definition of Complete Corresponding Source Code in the second

paragraph of section 1 is expansive, it is not sufficient to protect users'

freedoms in many circumstances. For example, a GPL'd program, or a modified

version of such a program, might need to be signed with a key or authorized

with a code in order for it to run on a particular machine and function

properly. Similarly, a program that produces digitally-restricted files might

require a decryption code in order to read the output.

The third paragraph of section 1 addresses this problem by making clear that

Complete Corresponding Source Code includes any such encryption,

authorization, and decryption codes. By requiring the inclusion of this

information whenever the GPL requires distribution of Complete Corresponding

Source Code, we thwart efforts to obstruct the goals of the GPL, and we

ensure that users will remain in control over their own machines. We

recognize an exception where use of the program normally implies that the

user already has the codes. For example, in secure systems a computer owner

might possess any keys needed to run a program, while the distributor of the

program might not have the keys.

% FIXME: installation information

%FIXME: publicly documented format

\section{Understanding License Compatibility}

\label{license-compatibility}

\section{GPLv3~\S7: Explicit Compatibility}

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

In GPLv3 we take a new approach to the issue of combining GPL'd code with

code governed by the terms of other free software licenses. Our view, though

it was not explicitly stated in GPLv2 itself, was 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, we supplemented this policy with a structure of

exceptions for certain kinds of combinations.

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

Section 7 of GPLv3 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. We

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.

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

Section 7 first explicitly allows added parts covered by terms with

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

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.

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

In its treatment of terms that impose additional requirements, section 7

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 section 7. We

must, of course, place some limit on the kinds of additional requirements

that we will accept, to ensure that enhanced license compatibility does not

defeat the broader freedoms advanced by 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 no such user

would have the right to do so.

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

Under subsections 7a and 7b, the requirements may include preservation of