The Portable Class Library project enables you to write and build managed assemblies that work on more than one .NET Framework platform (Silverlight, WP7, or XNA).
Using the Portable Class Library project, you can build portable assemblies that work without modification on the .NET Framework, Silverlight, Windows Phone 7, or XNA (Xbox) platforms. Without the Portable Class Library project, you must target a single platform and then manually rework the class library for other platforms. The Portable Class Library project supports a subset of assemblies from these platforms, and provides a Visual Studio template that makes it possible to build assemblies that run without modification on these platforms.
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