Wrote section on two copylefts.

gpl-lgpl.tex

@@ -933,6 +933,29 @@ Section~\ref{GPlv3S14}.
 
 \section{Complexities of Two Simultaneously Popular Copylefts}
 
+Obviously most GPL advocates would prefer widespread migration to GPLv3, and
+many newly formed projects who seek a copyleft license tend to choose a
+GPLv3-based license.  However, many existing copylefted projects continue
+with GPLv2-only or GPLv2-or-later as their default license.
+
+While GPLv3 introduces many improvements --- many of which were designed to
+increase adoption by for-profit companies --- GPLv2 remains a widely used and
+extremely popular license.  The GPLv2 is, no doubt, a good and useful
+license.
+
+However, unlike GPLv1, which (as pointed out in \S~\ref{GPLv1}), which is
+completely out of use by the mid-1990s.  However, unlike GPLv1 before it,
+GPLv2 remains a integral part of the copyleft licensing infrastructure for
+some time to come.  As such, those who seek to have expertise in current
+topics of copyleft licensing need to study both the GPLv2 and GPLv3 family of
+licenses.
+
+Furthermore, GPLv3 can is more easily understood by first studying GPLv2.
+This is not only because of their chronological order, but also because much
+of the discussion material available for GPLv3 tends to talk about GPLv3 in
+contrast to GPLv2.  As such, a strong understanding of GPLv2 helps in
+understanding most of the third-party material found regarding GPLv3.  Thus,
+the following chapter begins a deep discussion of GPLv2.
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 \chapter{GPLv2: Running Software and Verbatim Copying}