The VC Directory buffer is a specialized buffer for viewing the version control statuses of the files in a directory tree, and performing version control operations on those files. In particular, it is used to specify multi-file VC filesets for commands like C-x v v to act on (see VC Directory Commands).
To use the VC Directory buffer, type C-x v d (
This reads a directory’s name using the minibuffer, and switches to a VC
Directory buffer for that directory. By default, the buffer is named
*vc-dir*. Its contents are described
in The VC Directory Buffer.
vc-dir command automatically detects the version control
system to be used in the specified directory. In the event that more
than one system is being used in the directory, you should invoke the
command with a prefix argument, C-u C-x v d; this prompts for
the version control system which the VC Directory buffer should use.
In addition to the VC Directory buffer, Emacs has a similar facility called PCL-CVS which is specialized for CVS. See About PCL-CVS in PCL-CVS—The Emacs Front-End to CVS.
You can also invoke VC commands from Dired buffers (see Dired, the Directory Editor). In that case, any VC command you invoke considers the marked files as the current fileset (see Basic Editing under Version Control), defaulting to the file on the current line if no files are marked.