retargetable assembly(An assembly that belongs to more than one implementation of the .NET Framework, or an assembly that has been built on more than one implementation of the .NET Framework with the same strong name and with appropriate attributes. Applications that use retargetable assemblies can run on any .NET Framework implementation where those assemblies have been built. For example, applications that are built to use the .NET Compact Framework can run on the desktop implementation of the .NET Framework)
