“Interoperation with Microsoft products is difficult while Microsoft continues to embrace and extend protocols developed in an open source manner, and along with Microsoft developed protocols and file formats, license the result in a manner unacceptable to competing vendors. In the field of digital media, Microsoft does not make its media player codecs available to the Linux platform.”

Most of the protocols that Microsoft has licensed under the Microsoft Communications Protocol Program are derived for freely implementable open standards, or like in the case of Kerberos, open source code.

The terms that Microsoft relicense the result is unacceptable to even most proprietary software vendors.