Its license terms have been approved by the Open Source Initiative and Free Software Foundation. The CPL's stated aims are to support and encourage collaborative open source development, while still retaining the ability to use the CPL'd content with software licensed under other licenses, including many proprietary licenses. The Eclipse Public License (EPL) is a slightly modified version of the CPL.
The CPL has some terms that are similar to the GNU General Public License, but there are some key differences. One difference is in a patent clause designed to prevent contributors from contributing code which infringes on their patents, and then attempting to charge royalties; in such a situation, the CPL requires the contributor to grant a royalty-free license to all recipients. This additional requirement renders the CPL incompatible with GPL version 2 in the opinion of Eben Moglen, and the GNU website. A similarity is related to a distribution of a modified program: under either license (CPL or GPL), one is obligated to make the source code to the modified Program available to others.
CPL, like the GNU Lesser General Public License, allows non-CPL-licensed software to be linked to a library under CPL without requiring the linked source code to be made available to the licensee.
CPL is incompatible with GPLv3 because it has a "choice of law" section in section 7, which restricts legal twists to a certain court. It is also incompatible with GPLv2 because of this, and also because of the patent clauses as mentioned above. 
Microsoft has released their Windows Installer XML (WiX) developer tool, Windows Template Library (WTL) and the FlexWiki engine under the CPL as Sourceforge projects. IBM, along with several people from academia started CPL licensed coin-or projects to provide free and open source software relating to optimization and operational analysis. The initiative led to establishment of the COIN-OR Foundation.
- CPL Frequently Asked Questions
- Open Source Initiative The CPL License
- The CPL License from IBM
- The COIN-OR web pagede:Common Public License