Microsoft has released an early draft of the specifications for XAML and WPF under the Microsoft Open Specification Promise. This offers patent protection for implementers against claims by Microsoft, allowing open source projects to use the specifications.
The Microsoft Open Specification Promise essentially says that if Microsoft has a patent on a covered specification, then the patent will never be enforced against any implementation of said specification. They do not however promise to indemnify implementers against non-Microsoft patents.
Microsoft irrevocably promises not to assert any Microsoft Necessary Claims against you for making, using, selling, offering for sale, importing or distributing any implementation to the extent it conforms to a Covered Specification (“Covered Implementation”), subject to the following. This is a personal promise directly from Microsoft to you, and you acknowledge as a condition of benefiting from it that no Microsoft rights are received from suppliers, distributors, or otherwise in connection with this promise. If you file, maintain or voluntarily participate in a patent infringement lawsuit against a Microsoft implementation of such Covered Specification, then this personal promise does not apply with respect to any Covered Implementation of the same Covered Specification made or used by you. To clarify, “Microsoft Necessary Claims” are those claims of Microsoft-owned or Microsoft-controlled patents that are necessary to implement only the required portions of the Covered Specification that are described in detail and not merely referenced in such Specification. “Covered Specifications” are listed below.
This promise is not an assurance either (i) that any of Microsoft’s issued patent claims covers a Covered Implementation or are enforceable or (ii) that a Covered Implementation would not infringe patents or other intellectual property rights of any third party. No other rights except those expressly stated in this promise shall be deemed granted, waived or received by implication, exhaustion, estoppel, or otherwise.
The XAML specifications are divided into two parts. First is the Xaml Object Mapping Specification. This defines the XAML language itself and focuses heavily on parsing. The second specification is the WPF Xaml Vocabulary Specification. This covers the objects found in the Windows Presentation Foundation. Unlike the Object Mapping specification, the Vocabulary specification is more of an outline that a true specification at this stage.