Retargetable Merge Modules
By default, files in merge modules are installed into the folder locations specified by the author of the merge module using the File System Editor. In some cases, you may want to allow the consumer of the merge module some flexibility in deciding where files should be installed for their application. For example, if an assembly in a merge module is used by multiple applications, the consumer of the merge module may want to install it in the global assembly cache; otherwise, they would install it in the application directory.
To allow the consumer of a merge module to retarget a file to a different location, place the file in the Module Retargetable folder in the File System Editor. When the resulting merge module is added to another deployment project, the author of that project can choose a location by setting the Module Retargetable Folder property exposed by the merge module. The Module Retargetable Folder property is a dynamic property; it appears under the (MergeModuleProperties) node beneath the KeyOutput node in the Properties window when a merge module is selected in Solution Explorer.
Note If you change the name of the Module Retargetable folder in the File System Editor, the name of the property will be changed, as well. The property will not show up in the Properties window until the merge module has been built.