Chapter 546. Software: basic steps and differences according to the various licenses

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Software is a code protected from copyright laws, similarly to what happens for literary works. Usually, the contract that rules the use of software is the license; is always important to know deeply the terms of the license agreement for the software you intend to deal with.

Software always has an owner, except for public domain software (which is covered later in this book), which is such because he "owns the copyright". This owner can be the original author or maybe another holder which has gained the rights with a contract. The holder of the copyright becomes the owner of the work.

Use of the software can be granted for free or upon a payment. Paying does not mean "purchasing" the software, but just dealing with it according to what is written in the license.

Nature of the software is comprised of two different parts: source code and executable code. The first one is human readable, while the second one is suited for machine execution and not for reading. Since only the executable part is needed to make software operate, software copyright preservation laws that exist in many countries do permit distribution of the executable code alone, allowing the copyright owner to keep the source code hidden. Following the same path, laws in these countries tend to put an illicit mark over reverse engineering of the software. The latter is the study of the executable code geared towards learning how code operates.

In many countries you may also be able to patent algorithms and other concepts tied to software. This way, the patent doesn't allow the use of the algorithm or protected idea without an explicit authorisation from the owner of the copyright.

Figure 546.1. Classification of software; drawn by Chao-Kuei, obtained from the FSF website.

figure/a2-software-categorie

546.1 Free software

Free software is such if it does allow usage by everybody, copy and distribution of it, both in its original form and its modifications, for free or even by selling it. Free software can be such only if it's offered along with source code. To this extent someone said: "If it's not source, it's not software".

It's important to note that "freedom" of free software is not in the price - which can also be requested for the distribution service - but the possibility to use it without restrictions, to copy it as many times as you want, to distribute it and to modify it and even distribute the modified copies.

Some people prefer to use the "Open Source" tag to identify free software in the terms we have described above.

We can focus on four basic concepts, all of which are needed to refer to software as "free".

Freedom 0, freedom to execute the program for whatever reason;
Freedom 1, freedom to study and learn how the program operates and the ability to modify it to best suit your own needs (in such a case source code is needed);
Freedom 2, freedom to redistribute copies of the program;
Freedom 3, freedom to improve the program and to distribute such improvements (also for this one we need the source code).

Software which can not be sold, even though satisfying the four basic concepts listed here is not going be considered free software in this written work.

It's worth mentioning some definitions concerning free software.

Public domain software

Public domain software is software without copyright. On its own this software it's free, but since it has no copyright it doesn't have a license either, so anybody is free to do whatever he wants with it, even take ownership of the rights. This means some copies or variations of this software are no more free.
copyleft protected software

The word copyleft is an invention and represents the copyright of who, while defending his rights as the author, wants to defend freedom of his work, imposing that the original version of his work and derivated ones are kept free. Shortly, a license belonging to the "copyleft" category blocks additional restrictions applied to it from who is going to redistribute the software (modified or original whatever) at the moment. A typical example of this kind of license is the GNU-GPL public license (section A).
free software not protected by copyleft

Free software is not necessarily copylefted and this happens when the license does not explicitly forbid applying additional restrictions from who redistribute the software. To use software of this kind it's important to check carefully the terms of the agreement concerning the particular copy or version of the software we have.
GPL'ed software

The GNU-GPL license is the most important example of license that protects free software with copyleft. When referring to "GPL'ed software" you are indicating software which is protected by the GNU-GPL public license.

546.2 Non-free software

Software is not free when all the minimal requisites to classify it as such are not satisfied. It's a good thing to remember that price is not a thing that limits freedom and that other details are much more important. Also this time, it is worth listing some definitions for non-free software.

semi-free software

Semi-free software is software that allow usage, copy, modification and distribution even after a modification for whatever reason except to make profit out of it. In other words we could say that is free software with a limitation on usage and distribution for profit. This is a detail that must not be forget.
proprietary software

Proprietary software is the one that is nor free neither semi-free. Usually, to deal with it it is necessary to obtain a special permission, that most of the time limits its usage to just one computer or a well-defined environment.
- freeware software
  
  The freeware word is not tied to a strict definition, but usually refers to software that is freely available but doesn't come along with the source. It can be copied and used but not modified. Meant this way the "free" prefix is only used to spot that there's no price set on it, but is fairly different from freedom, which asks for more requisites.
- shareware software
  
  With the shareware word we refer to proprietary software that you are required to buy after a trial period even if it can be freely distributed.

546.3 Commercial software

According to the various classifications explained in this chapter, commercial software is such, only because it's sold for profit. One of the basic elements of free software is the possibility to sell original or modified copies to make profit out of it. Following this subtle difference it is important to spot out the difference of proprietary software from commercial software because they're not the same thing.

To better understand or mess up things as well, we can add that both non-free and non-commercial software do exist.

546.4 Notes on some licenses

The document Various Licenses and Comments about Them that you can get at <http://www.gnu.org/philosophy/license-list.html>, makes a detailed list of characteristics of a many licenses. It is worth pointing out here some licenses that are not born from the Free Software Foundation.

Table 546.1. This table helps spotting the main differences between some common licenses according to information published by Free Software Foundation in the document Various Licenses and Comments about Them that you can get at <http://www.gnu.org/philosophy/license-list.html>. First part.

Denomination	Acronym	Free software according to the minimum terms of the definition	Copyleft	GNU-GPL compatible	Non-free software compatible	Notes
GNU General Public License	GPL	Yes	Yes	Yes	No
GNU Lesser General Public License	LGPL	Yes	Yes	Yes	Yes
X11 or MIT	X11	Yes	No	Yes	Yes
Cryptix General License		Yes	No	Yes	Sė
Non-Berkeley BSD		Yes	No	Yes	Yes	There's too much confusion around the BSD acronym, too many licenses similar to the Berkeley one are released under its name.
W3C	W3C	Yes		Yes
Clarified Artistic License		Yes	No	Yes

Table 546.2. This table helps spotting the main differences between some common licenses according to information published by Free Software Foundation in the document Various Licenses and Comments about Them that you can get at <http://www.gnu.org/philosophy/license-list.html>. Second part.

Denomination	Acronym	Free software according to the minimum terms of the definition	Copyleft	GNU-GPL compatible	Non-free software compatible
Arphic Public License		Yes	Yes	No
Original BSD	BSD	Yes	No	No	Yes
Zope Public License		Yes	No	No
Apache License		Yes	No	No
OpenLDAP		Yes	No	No
IBM Public License		Yes		No
Phorum License		Yes		No
LaTeX Project Public License	LPPL	Yes		No
Mozilla Public License	MPL	Yes		No
Netizen Open Source License	NOSL	Yes		No
Interbase Public License		Yes		No
Sun Public License		Yes		No
Nokia Open Source License		Yes		No
Netscape Public License	NPL	Yes		No
Jabber Open Source License		Yes		No
Sun Industry Standards Source License		Yes		No
Qt Public License	QPL	Yes		No
FreeType License		Yes	No	No
Open Compatibility License		Yes		No

Table 546.3. This table helps spotting the main differences between some common licenses according to information published by Free Software Foundation in the document Various Licenses and Comments about Them that you can get at <http://www.gnu.org/philosophy/license-list.html>. Third part.

Denomination	Acronym	Free software according to the minimum terms of the definition	GNU-GPL compatible	Notes
Artistic License	Artistic	No	No	Bad formulated license.
Apple Public Source License	APSL	No	No
Sun Community Source License		No	No
Plan 9 License		No	No
Open Public License		No	No
Sun Solaris Source Code License		No	No
YaST License		No	No

546.4.1 Artistic license

The original Artistic license is by most people considered a bad formulated license, too vague and thus not good for preserving software freedom. Under this perspective it is not included in the free software category.

To put a remedy in the holes of the Artistic license, a new revision called Clarified Artistic License was developed.

546.4.2 BSD license

The original BSD license contains an explicit reference to the Berkeley university and explicitly states that the name cannot be used for advertising. Even if this concept doesn't create any problem for software usage, it is not convenient to adopt this license if you don't have such a need. Anyway this point doesn't make the BSD license good for general purpose usage and most importantly generates some compatibility problems with the GNU-GPL license.

Trying to avoid this little disadvantage different modified versions of this license have been created. Unfortunately, a neat definition for this license does not exist and people tend to simply name them BSD licenses, feeding confusion that should be better to avoid.

546.4.3 QPL license

The QPL license QPL has been known in the past because it was developed for the Qt graphical library but is incompatible with the GNU-GPL license and makes some restrictions regarding distribution of modified code.

546.5 References

Categories of Free and Non-Free Software

<http://www.gnu.org/philosophy/categories.html>

<http://www.fsf.org/philosophy/categories.html>
Various Licenses and Comments about Them

<http://www.gnu.org/philosophy/license-list.html>

<http://www.fsf.org/philosophy/license-list.html>
The Free Software Definition

<http://www.gnu.org/philosophy/free-sw.html>

<http://www.fsf.org/philosophy/free-sw.html>
Some Confusing or Loaded Words and Phrases that are Worth Avoiding

<http://www.gnu.org/philosophy/words-to-avoid.html>

<http://www.fsf.org/philosophy/words-to-avoid.html>

1) Translation last update on 2002.02.22 from Simone Caronni slaanesh @ fastwebnet.it (original chapter was 1).