GNU General Public License 2.0 (GPL2)
07月 17, 2009Written by 葛冬梅 Florence T.M. Ko
I. Overview
The GPL is originally written by Richard Stallman, who believes that software users shall be entitled to the following four freedoms : the freedom to run, study and improve the program, and to release the improvements to the public, so that the whole community benefits. He also initiated the “GNU Project”, in order to develop an operating system that fulfills the four freedoms. To make his idea legally effective, Stallman first designed a software licensing mechanism which is unlike any existing licenses – the “copyleft”. He then wrote the GPL with the copyleft-minded spirit. The GPL becomes a legally binding license document. It is employed by most programs listed on GNU Project.
Version 1 of the GPL (GPL1) was released in 1989, while version 2 of the GPL (GPL2) was released in 1991 and has been used since then. The current copyright holder of the GPL2 – the Free Software Foundation (FSF) – has announced the draft of the version 3 of the GPL (GPL3). It is expected that after the year-long public consultation process, the GPL3 will be finalized in 2007.
II. Current Status
Many of the well-known free/open source softwares are licensed under the GPL2, including Linux, MySQL, Gaim, Samba, LAME, gcc, Qt, Ethereal, and so on. According to the survey on the Freshmeat website (http://freshmeat.net/stats/#license), free/open source softwares licensed under the GPL2 are far more than the other licenses.
III. Rights and Duties
Below is the list of the essential terms and conditions of the GPL2. The goal of the short despription is to help you understand the GPL2, thus the details are not included here. You have to read the full text of the GPL2, or seek for other consultations, should you need more information.
1. Rights
The following rights are licensed under the GPL2:
(1) the right to run the program;
(2) the right to copy the program;
(3) the right to distribute the program; and
(4) the right to modify the program.
2. Duties
The duties are closely related to the above-mentioned rights. In other words, when a licensee is exercising his right granted by the GPL2, he has to comply with the following duties. When violated, all licensed rights will be automatically terminated.
(1) When distributing the original work
A licensee has to comply with the following obligations when distributing the source code of the GPL2 program.
(A) The licensee must distribute verbatim copies of the program’s source code;
(B) The licensee has to retain all the accompanying notices, including the copyright notice and disclaimer of warranty;
(C) The licensee must give any other recipients of the program a copy of this GPL2 along with the program.
(2) When distributing the modified work
A licensee can modify the program or any portion of it, and distribute such modifications or work under the terms mentioned above, provided that he also meet all of these following conditions:
(A) The licensee must cause the modified files to carry prominent notices stating that you changed the files and the date of any change;
(B) The licensee must cause any modified work licensed under the terms of the GPL2;
(C) If the modified program normally reads commands interactively when run, the licensee must ensure that the recipients of the program are able to print or read the copyright notice and the disclaimer of warranty.
(3) When distributing the program in object code
A licensee may distribute the program or the modified copies in the forms of either source code or object code. However, the licensee must provide the recipients with a complete source code in one of the following methods, when distributing the program in object code::
(A) The licensee may distribute the source code and the object code simultaneously. He must, however, provide the complete corresponding machine-readable source code on a medium customarily used for software interchange, e.g. the CD-ROM.
(B) The licensee may accompany the object code with a written offer, valid for at least three years, to give any third party, for a charge no more than the cost of physically performing source distribution, a complete machine-readable copy of the corresponding source code; or,
(C) If the licensee received the program in object code form with such an offer, in accord with Subsection B above, he may accompany it with the information he received as to the offer to distribute corresponding source code. This alternative is allowed only for noncommercial distribution.
(D) The licensee may distribute the source code by offering access to copy it from a designated place. The designated place means a fixed place on the Internet. The condition for this alternative is that the object code must be distributed through the same fixed place. The Uniform Resource Locators offering access to the object code and the source code may not be quite the same. Nonetheless, as long as an ordinary people can recognize them as the same place, it is sufficient, e.g. offering access links to copy both the object code and the source code at the same page.
IV. Other Terms and Condition
1. Modifying the GPL2 is prohibited;
2. The GPL2 does not contain specific terms on patent license or litigation, but patent is mentioned in its illustrative examples. If, as a consequence of allegation of patent infringement or for any other reason, GPLed programs are limited in some geographical areas, the licensee can take certain measures to respond.
3. Modifications of the GPL2 programs must also be licensed under the GPL2. However, it is not clear as to what the “modification” really means. Besides, there is no relevant court decision either. Therefore, how broad has the “modification” been covered in the GPL2 is an unsettled issue.
