The source code for the .NET Framework will be available under Microsoft's Reference Licensing program, the most restrictive of Microsoft's shared source licenses. The license allows developers to view the source code, but neither modify nor redistribute it. It could help some current .NET developers find and fix particularly difficult bugs in their applications but will do little to entice new developers to the .NET platform.

Providing developers the source code for the Framework enables them to use the Visual Studio debugger to step from the source code of their own application into the source code of the Framework. By being able to see in detail how their code interacts with the Framework, developers may be able to find bugs in their code that would otherwise be very difficult to locate.

But the move does little to change the competitive landscape. Java and Adobe's Flex framework (which is built on Flash) are already available under more permissive licenses than Microsoft is providing. Java is provided under the GNU Public License and Flex under the Mozilla Public License. Both permit developers to not only view the source code but also make and distribute modifications as well.

Microsoft's Shared Source programs are described in "Shared Source Licensing Simplified" on page 32 of the Dec. 2005 Update.