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Free software licenses, definitions, types and compatibility

Posted by Pablo Gonzalez on January 8th 2013

In this article we will continue with free software licenses, definitions, types and compatibility.

Therefore, we will initially treat several definitions and subsequent years of introduction:

- Freeware: These are free programs that are usually distributed compiled. If we want to redistribute such software usually must ask the author permission. This type of software is used for propaganda in other software with more features and usually pay.

- Shareware: It is a method where the program distribution may be limited in function of a time period. Payment is usually done because these programs have propaganda, limited functions, etc ...

- Public Domain: The author waives his rights and give them to mankind. By default, a program that does not specify anything in the public domain, therefore, must be expressly stated in the software.

- Permissive licenses: Non-copyleft license that allows distributing the software under another license. Could even distributed under a proprietary license. Example, BSD.

- Licenses robust (copyleft): The license requires that the modifications are distributed free. Example, GPL.

It is important to examine and verify the licenses are not mutually incompatible. For example, a program that blends a license GPLv3 GPLv2 with inconsistent because GPLv3 violate Article 6 of GPLv2 as this does not allow adding more restrictions. If we use the GPLv3 add the restriction to provide information on facilities. From this it generates a mismatch.

Keep in mind that we want to license our software, as it will be compatible or not with other changes becoming more difficult in the future.

As a personal opinion, nowadays, prefer permissive licenses that allow even a modification under a proprietary license. This I consider a paradox, since the warrant permissive freedoms of all (even those who want to make it exclusive), but on the other band, each eliminates proprietary license and freedoms goes against keeping them.

Nevertheless, I think it is best that everyone can choose what they want to do with their freedom.

NOTE: The Linux project is generated GPLv2 licensed. The use of DRM systems can implement GPLv3 * restricting modifications to the program code not authorized by the hardware. What will happen to our open source software is not signed by the hardware? Decide yourself ...

* They are mechanisms or rights management technology to protect digital copyrights.

Now remember the freedoms 4:

a) The freedom to run the program for any purpose.

b) freedom to study the program, modify it as needed. We need access to the source code.

c) freedom to distribute copies of the program.

d) freedom to improve the program and launch it. We need access to the source code.


- The type of software Freeware grants users access to the source code and allows modification and study. True or false?

- The free software licenses allowed to be redistributed as proprietary software? True or false?

- Imagine a program with modified GPL license, do requires us to distribute the modified source code?

- Why is the original BSD license 4 clauses incompatible with the BSD GPLv2 but 3 clauses if it is compatible?

In the following article we will see some more examples of dual licensing software, discuss project management models and some exercises and examples.

I hope you find it useful.

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Early free software II

Posted by Pablo Gonzalez on June 9th 2012

“Si tu tienes una manzana y yo tengo otra manzana y la intercambiamos, los dos seguimos teniendo una manzana, pero si tu tienes una idea y yo tengo otra idea los dos tendremos dos ideas”.

Bernard Shaw

This is one of my favorite lines, but in the times in which we are, where the licenses and rights are the order of the day and we played a lawsuit, this is not so easy.

For this reason, in this article we will deal especially basic legal issues in subsequent articles and talk of free licenses.

Intellectual property:

We can identify the intellectual property copyright (copyright) that protect the works from unauthorized copying.

Intellectual property is protected and coordinated by the World Intellectual Property Organization (WIPO) by the agreements which are forced in the participating countries of the World Trade Organization to comply.

The Universal Declaration of Human Rights recognizes in its articles the right to moral and material rights of their works are protected, so that his philosophy is to try the authors of the idea "reward". Remarkably, when the promotion ends or validity, intellectual property expires.

The mission is that through intellectual property can provide a competitive advantage to the author of the idea to exploit during the term of intellectual property.


Initially it was created to protect rights to authors of art and books.

This protection helps protect ideas, expressions and knowledge. What you need to be very, very clear it is that these rights are immediately begin to publish the work, but not put (c) in our work.

Example, I make a picture and the public without indicating that the public domain or any other license, this photograph has a copyrigh, copyright preventing any use without notice and in case of breaching it can proceed with a lawsuit.

If you want to protect a copyrighted work recommend going to the notary and protect it. In this way we can show later copies.

Formalized by the Berne Convention in 1886.

Patents and trademarks:

At this point I will be very brief, patents and trademarks are registered because normally represents quality and value in a market.

The curiosity here is that this type of law is provided from the 15 25 the years.

View this site ya que es muy interesante para buscar patentes y marcas en Europa, y en USA podemos usar la página

As an example, I searched the trademark "LinEx" distribution created in Extremadura for a very interesting project discussed below, and I found:


  • Case file: M 2449568
  • Distinctive Type: D
  • Date of situation: 16/11/2002
  • Nice Classification: 09

Hence, we can extract much information, but something that is not so obvious is the "Nice Classification" which is a standard that informs us of the classification of this brand. To view this classification see the following page:

Trade secret:

Based on the advantage in that the company protects their works through industrial property.

A typical example may be the evil empire, where their proprietary programs compiled and provided to us to reverse engineer is considered a crime.

Let's look at the license for example Windows XP, paragraph 4:


DISASSEMBLY. You may not reverse engineer, decompile, or

disassemble the Software, except and only to the extent that such activity is expressly

permitted by applicable law notwithstanding this limitation.

In the next issue we start with the free licenses, definitions, types and compatibility.

I hope you find it useful.

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