Currently, FSF focused on GNU projects supervision and internal publications while OSI works toward marketing and legitimating OSS movement in the eyes of mainstream business community (Feller, J. and Fitzgerald, B., 2002). .
FSF initially created a licensing model called GPL that evolved and imitated into various copyleft licensing. Some of the most popular and most adopted licenses are as follow (Hecker, F., June 2000):.
• GPL (General Public License) or LGPL (Lesser GPL) termed as viral license as it required any code derived from GPL-ed code to be automatically included under GPL as well. Due to this nature, GPL is argued to be so far the most adopted copyleft licensing, up to 70.29% (LGPL rank 2 with 5.02%) from a total of 30,128 OSS branches software being tracked (http://freshmeat.net/stats/rating, June 2003).
• BSD or X License, as the third most adopted licensing model is considered giving the most freedom for creating derivative works.
• Artistic License, the next most adopted licensing, provides some exemptions on the GPL model, such as derived works that are not automatically fall under the same license and allows modified work to be closed source if it is only used within an organization.
• Mozilla Public License or Netscape Public License further removes some of the GPL licensing constraints whereby it allows creating add-on proprietary source code that interacts through APIs with original codes and licenses them for a fee.
Linux in further development have embraced GPL license which makes it inherits a few important characteristics of the copyleft licensing, described as follow:.
1. Linux distribution covered by GPL licenses ensures that it is available freely or with nominal fee to whoever needs it.
2. All Linux derived works are required or encouraged to be open source as well.
3. Try to minimize the restriction on the use of the Linux not only in developer communities but also for corporate markets.
