ciaran2014 writes With Microsoft proudly declaring its .NET runtime open source, a colleague and I decided to look at the licensing aspects. One part, the MIT licence, is straightforward, but there's also a patent promise. The first two-thirds of the first sentence seems to announce good news about Microsoft not suing people. Then the conditions begin. It seems Microsoft can't yet bring itself to release something as free software without retaining a patent threat to limit how those freedoms can be exercised. Overall, we found 4 Shifty Details About Microsoft's "Open Source" .NET.