Creating Multiple Versions of an Application or Component
You can create and run multiple versions of an application or component on a computer. For example, one version of an application could support the runtime that shipped with .NET Framework version 1.0 while another version of the same application could support the runtime that shipped with .NET Framework version 1.1. A compiled application or component contains a reference to the runtime version used to create the file. This reference can affect the version of the runtime that is used to run the application or component. For more information, see Determining Which Version of the Runtime to Load.