Is Windows Media DRM open and extensible?
Yes. The Windows Media DRM application programming interfaces (APIs) are open and published, which allows third parties to customize and extend their DRM systems. Microsoft only provides the core components. The various SDKs also allow third parties to build different media applications to support Windows Media, including Windows Media Rights Manager. For more information on the SDKs that are available for Windows Media client and server development, see Windows Media SDK Components.