Rework public domain section,

including cross referencing to new sections to be written,
and handling the FIXME.

gpl-lgpl.tex

@@ -349,23 +349,19 @@ Software. In an imaginary world with no copyright, the rules would be
 different. In this world, when you received a copy of a program's source
 code, there would be no default legal system to restrict you from sharing it
 with others, making modifications, or redistributing those modified
-versions.\footnote{There could still exist legal systems, like our modern
+versions.\footnote{Note that this is again an oversimplification; the
-  patent system, which could restrict the software in other ways, as well as
+  complexities with this argument are discussed in
-  technical measures, such as binary-only distribution, that impeded such activity.}
+  Section~\ref{software-and-non-copyright}.}
 
-Software in the real world is copyrighted by default and is
+Software in the real world is copyrighted by default and is automatically
-automatically covered by that legal system.  However, it is possible
+covered by that legal system.  However, it is possible to move software out
-to move software out of the domain of the copyright system.  A
+of the domain of the copyright system.  A copyright holder can often
-copyright holder can often \defn{disclaim} their
+\defn{disclaim} their copyright.  If copyright is disclaimed, the software is
-copyright.  If copyright is disclaimed, the software is not governed
+not governed by copyright law.   Software not governed by copyright is in the
-by copyright law. Software not governed by copyright is in the
 ``public domain.''
 
 \subsection{Public Domain Software}
-% FIXME: this section needs more improvements to make it clear that public
+
-% domain dedication is difficult, if not impossible.
-% Karen suggests that talking about USA government software being public
-% domain might make sense here.
 Theoretically, an author can create public domain software by disclaiming all
 copyright interest on the work. In the USA and other countries that have
 signed the Berne convention on copyright, software is copyrighted
@@ -392,6 +388,23 @@ is absent copyright and absent a license. The software freedoms discussed in
 Section~\ref{Free Software Definition} are all granted because there is no
 legal system in play to take them away.
 
+Admittedly, a discussion of public domain software is an oversimplified
+example.  First, disclaimer of copyright is actually difficult in practice.
+Because copyright controls are usually automatically granted and because, in
+some jurisdictions, some copyright controls cannot be waived (See
+Section~\ref{non-usa-copyright} for further discussion), many copyright
+holders sometimes incorrectly believe a work has been placed in the public
+domain.  Second, due to aggressive lobbying by the entertainment industry,
+the ``exclusive Right'' of copyright, that was supposed to only exist for
+``Limited Times'' according to the USA Constitution, appears to be infinite:
+simply purchased on the installment plan rather than in whole.  Thus, we must
+assume no works of software will fall into the public domain merely due to
+the passage of time.
+
+The best example of software known to be in the public domain is software
+that is published exclusively produced by the USA government.  Under
+\href{http://www.law.cornell.edu/uscode/text/17/105}{17 USC 101 \S 105}, all
+works published by the USA Government are not copyrightable.
 
 \subsection{Why Copyright Free Software?}