\label{GPLv3s4}

GPLv3~\S4 is a revision of GPLv2\~S1 (as discussed in \S~\ref{GPLv2s1} of

this tutorial).   There is almost no changes to this section from the

GPLv2\~S1, other than to use the new defined terms.

The only notable change of ``a fee'' to ``any price or no price'' in the

first sentence of GPLv3\S4\P2.  The GPLv2\S1\P1 means that the GPL permits

one to charge money for the distribution of software.  Despite efforts by

copyleft advocates to explain this in GPLv2 itself and in other documents,

there are evidently some people who still believe that GPLv2 allows charging

for services but not for selling copies of software and/or that the GPL

requires downloads to be gratis.  Perhaps this is because GPLv2 referred to

charging a ``fee''; the term ``fee'' is generally used in connection with

services.

GPLv2's wording also referred to ``the physical act of transferring.''  The

intention was to distinguish charging for transfers from attempts to impose

licensing fees on all third parties.  ``Physical'' might be read, however, as

suggesting ``distribution in a physical medium only''.

To address these two issues, GPLv3 says ``price'' in place of ``fee,'' and

removes the term ``physical.''

% FIXME: needs context, needs match up to current text, and removal of stuff

%        that's no longer there

% FIXME: say more and tie it to the text

There is no harm in explicitly pointing out what ought to be obvious: that

those who convey GPL-covered software may offer commercial services for the

support of that software.

\section{GPLv3~\S5: Modified Source}

\label{GPLv3s5}

% FIXME: 5(a) is slightly different in final version

Section 5 contains a number of changes relative to the corresponding section

in GPLv2. Subsection 5a slightly relaxes the requirements regarding notice of

changes to the program. In particular, the modified files themselves need no

longer be marked. This reduces administrative burdens for developers of

modified versions of GPL'd software.

Under subsection 5a, as in the corresponding provision of GPLv2, the notices

must state ``the date of any change,'' which we interpret to mean the date of