Virtual File System Index
Virtual File Systems which use the file extension .vfs can be used to so that client applications can can access different concrete file systems. An example of this is the accessing of both local and network storage systems. Through the use of virtual file systems it is also possible to access files from different operating and file systems such as those between Windows, Mac OS X and Unix due to the virtual file system the application doesn't know that it is accessing the file from another operating system.
Virtual File System files usually contain an index of directories and files and are not supposed to be opened by the user, these files also make the browsing and searching of data quicker.