2 Debugging with gdb
texts. Documentation is an essential part of any software package; when an important free
software package does not come with a free manual and a free tutorial, that is a major gap.
We have many such gaps today.
Consider Perl, for instance. The tutorial manuals that people normally use are non-free.
How did this come about? Because the authors of those manuals published them with
restrictive terms—no copying, no modification, source files not available—which exclude
them from the free software world.
That wasn’t the first time this sort of thing happened, and it was far from the last.
Many times we have heard a GNU user eagerly describe a manual that he is writing, his
intended contribution to the community, only to learn that he had ruined everything by
signing a publication contract to make it non-free.
Free documentation, like free software, is a matter of freedom, not price. The problem
with the non-free manual is not that publishers charge a price for printed copies—that in
itself is fine. (The Free Software Foundation sells printed copies of manuals, too.) The
problem is the restrictions on the use of the manual. Free manuals are available in source
code form, and give you permission to copy and modify. Non-free manuals do not allow
this.
The criteria of freedom for a free manual are roughly the same as for free software.
Redistribution (including the normal kinds of commercial redistribution) must be permitted,
so that the manual can accompany every copy of the program, both on-line and on paper.
Permission for modification of the technical content is crucial too. When people mod-
ify the software, adding or changing features, if they are conscientious they will change
the manual too—so they can provide accurate and clear documentation for the modified
program. A manual that leaves you no choice but to write a new manual to document a
changed version of the program is not really available to our community.
Some kinds of limits on the way modification is handled are acceptable. For example,
requirements to preserve the original author’s copyright notice, the distribution terms, or
the list of authors, are ok. It is also no problem to require modified versions to include
notice that they were modified. Even entire sections that may not be deleted or changed
are acceptable, as long as they deal with nontechnical topics (like this one). These kinds of
restrictions are acceptable because they don’t obstruct the community’s normal use of the
manual.
However, it must be possible to modify all the technical content of the manual, and then
distribute the result in all the usual media, through all the usual channels. Otherwise, the
restrictions obstruct the use of the manual, it is not free, and we need another manual to
replace it.
Please spread the word about this issue. Our community continues to lose manuals
to proprietary publishing. If we spread the word that free software needs free reference
manuals and free tutorials, perhaps the next person who wants to contribute by writing
documentation will realize, before it is too late, that only free manuals contribute to the
free software community.
If you are writing documentation, please insist on publishing it under the GNU Free
Documentation License or another free documentation license. Remember that this deci-
sion requires your approval—you don’t have to let the publisher decide. Some commercial
publishers will use a free license if you insist, but they will not propose the option; it is up