Apple Public Source License
The Apple Public Source License is the open source license under which Apple the Darwin operating system has made available.
The first version was only recognized by the Open Source Initiative, but the second version also meets the guidelines of the Free Software Foundation. The license has a weak copyleft, which, although the left allowed with proprietary libraries, but does not allow license change for released under this license code. The latter makes the APSL to the GNU General Public License incompatible. The FSF considers this as two major problems and recommends no new projects under this License spread. However, the improvement of source code that is already under the APSL is unproblematic for the FSF.
The license is different between the original and modified code. The creator of the code shall be solely liable for violations of the rights of third parties or by software patents. Changes to the source code must therefore be explicitly marked with date.