Microsoft has launched an attack on existing open source "licensing proliferation" claiming that the system is confusing and unnecessarily challenging for software developers.

Jason Matusow, director of Microsoft's Shared Source Initiative, told vnunet.com that the large number of open source licences currently in use is counterproductive. 

"I believe that there are 55 or 56 open source approved licences. These have come about because source code is somebody's property and they have chosen to license according to their needs. We believe that developers should license code as they see fit," he said.

"But the biggest challenges come from additional licences. Let's say I'm a developer and I want to take code from both Python and Apache, which are both covered by open source licences. Are there any licensing issues by mixing code covered by different licences?

"In this specific case I know that there are no issues, but different licences create conflicts and sometimes challenges. What are the implications of one licence with the next? We cannot answer for everyone, but we can make sure that our licences are simple and predictable."

In a bid to simplify its own source code licensing Microsoft today unveiled three newly drafted template licences for its so-called Shared Source Initiative, which is designed to give developers, customers and partners access to the source code for Windows and other software.

The Microsoft Permissive Licence is the least restrictive of the Microsoft source code licences. It allows developers to view, modify and redistribute the source code for either commercial or non-commercial purposes.

Under the Permissive Licence, developers may change the source code and share it with others, and can charge a licensing fee for modified work.

The Microsoft Community Licence is designed for use on collaborative development projects. This type of licence is commonly referred to as a reciprocal source code licence and carries specific requirements if software engineers choose to combine Community Licence code with their own code.

It allows for both commercial and non-commercial modification and redistribution of licensed software.

The final licence unveiled today is the Microsoft Reference Licence which only allows licensees to view source code. It does not allow for modification or redistribution.

Matusow said that Microsoft has "learned from the open source community" and has made some code and some projects available, many via open source-like licences and some via other means.

The firm pointed out that it has more than 80 source code offerings that span the Windows and Office platforms and include projects that the open source community is helping to develop, such as the Windows Installer XML project.

However, Matusow went on to deny that Microsoft has been forced to open up access to its code because of the fast growing popularity of open source offerings.

"I would disagree with the notion that we have been forced into making these licensing changes," he said. "Most people are not aware that in 1992 Microsoft was sharing the source code of Windows with key partners."

In conjunction with the three shared source licence types, Microsoft announced that eight Starter Kits for Visual Studio 2005 and the next version of the Windows CE Bluetooth Wrapper will be offered under its Microsoft Permissive Licence.