However, in isolation, (a) would be too permissive, as it would sometimes

allowing distributors to evade important GPL requirements.  Part (b) reigns

in (a).  Specifically, (b) specifies only a few functionalities that a the

system library may provide and still qualify for the exception.  The goal is

to ensure system libraries are truly adjunct to a major essential operating

system component, compiler, or interpreter.  The more low-level the

functionality provided by the library, the more likely it is to be qualified

for this exception.

Admittedly, the system library exception is a frequently discussed topic of

obsessed GPL theorists.  The amount that has been written on the system

library exception (both the GPLv2 and GPLv3 versions of it), if included

herein,  could easily increase this section of the tutorial to a length

greater than all the others.

Like any exception to the copyleft requirements of GPL, would-be GPL

violators frequently look to the system library exception as a potential

software freedom circumvention technique.  When considering whether or not a

library qualifies for the system library exception, here is a pragmatic

thesis to consider, based on the combined decades of experience in GPL

interpretation of this tutorial's authors: the harder and more strained the

reader must study and read the system library exception, the more likely it

is that the library in question does not qualify for it.

\section{GPLv3~\S2: Basic Permissions}

% FIXME: phrase ``unmodified Program'' appears due to User Products exception

We have included the first sentence of section 2 to further internationalize

the GPL. Under the copyright laws of some countries, it may be necessary for

a copyright license to include an explicit provision setting forth the

duration of the rights being granted. In other countries, including the

United States, such a provision is unnecessary but permissible.

The first paragraph of section 2 also acknowledges that licensees under the

GPL enjoy rights of copyright fair use, or the equivalent under applicable

law. These rights are compatible with, and not in conflict with, the freedoms

that the GPL seeks to protect, and the GPL cannot and should not restrict

them.

% FIXME: propagate and convey

Section 2 distinguishes between activities of a licensee that are permitted

without limitation and activities that trigger additional requirements. The

second paragraph of section 2 guarantees the basic freedoms of privately

modifying and running the program. However, the right to privately modify and

run the program is terminated if the licensee brings a patent infringement

lawsuit against anyone for activities relating to a work based on the

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

termination was motivated in part to facilitate enforcement in European

countries.  We also believe the revised wording will be easier to understand

and apply in all jurisdictions.

\section{GPLv3~\S9: Acceptance}

% FIXME: needs some work here

Section 9 means what it says: mere receipt or execution of code neither

requires nor signifies contractual acceptance under the GPL.  Speaking more

broadly, we have intentionally structured our license as a unilateral grant

of copyright permissions, the basic operation of which exists outside of any

law of contract.  Whether and when a contractual relationship is formed

between licensor and licensee under local law do not necessarily matter to

the working of the license.

\section{GPLv3~\S10: Explicit Downstream License}

% FIXME: needs filled out and more here.

Draft1 removed the words ``at no charge'' from what is now subsection 5b, the

core copyleft provision, for reasons related to our current changes to the

second paragraph of section 4: it had contributed to a misconception that the

GPL did not permit charging for distribution of copies.  The purpose of the

``at no charge'' wording was to prevent attempts to collect royalties from

third parties.  The removal of these words created the danger that the

imposition of licensing fees would no longer be seen as a license

violation.

We therefore have added a new explicit prohibition on imposition of licensing

fees or royalties in section 10.  This section is an appropriate place for

such a clause, since it is a specific consequence of the general requirement

that no further restrictions be imposed on downstream recipients of

GPL-covered code.

Careful readers of the GPL have suggested that its explicit prohibition

against imposition of further restrictions\footnote{GPLv2, section 6; Draft

  3, section 10, third paragraph.} has, or ought to have, implications for

those who assert patents against other licensees.  Draft 2 took some steps to

clarify this point in a manner not specific to patents, by describing the

imposition of ``a license fee, royalty, or other charge'' for exercising GPL

rights as one example of an impermissible further restriction.  In Draft 3 we