+`C-x C-q'
+ Check the visited file in or out.
+
+`C-x v u'
+ Revert the buffer and the file to the last checked in version.
+
+`C-x v c'
+ Remove the last-entered change from the master for the visited
+ file. This undoes your last check-in.
+
+`C-x v i'
+ Register the visited file in version control.
+
+(`C-x v' is the prefix key for version control commands; all of these
+commands except for `C-x C-q' start with `C-x v'.)
+
+ When you want to modify a file maintained with version control, type
+`C-x C-q' (`vc-toggle-read-only'). This "checks out" the file, and
+tells RCS or SCCS to lock the file. This means making the file
+writable for you (but not for anyone else).
+
+ When you are finished editing the file, type `C-x C-q' again. When
+used on a file that is checked out, this command checks the file in.
+But check-in does not start immediately; first, you must enter the "log
+entry"--a description of the changes in the new version. `C-x C-q'
+pops up a buffer for you to enter this in. When you are finished
+typing in the log entry, type `C-c C-c' to terminate it; this is when
+actual check-in takes place.
+
+ Once you have checked in your changes, the file is unlocked, so that
+other users can lock it and modify it.
+
+ Emacs does not save backup files for source files that are maintained
+with version control. If you want to make backup files despite version
+control, set the variable `vc-make-backup-files' to a non-`nil' value.
+
+ Normally the work file exists all the time, whether it is locked or
+not. If you set `vc-keep-workfiles' to `nil', then checking in a new
+version with `C-x C-q' deletes the work file; but any attempt to visit
+the file with Emacs creates it again.
+
+ It is not impossible to lock a file that someone else has locked. If
+you try to check out a file that is locked, `C-x C-q' asks you whether
+you want to "steal the lock." If you say yes, the file becomes locked
+by you, but a message is sent to the person who had formerly locked the
+file, to inform him of what has happened. The mode line indicates that
+a file is locked by someone else by displaying the login name of that
+person, before the version number.
+
+ If you want to discard your current set of changes and revert to the
+last version checked in, use `C-x v u' (`vc-revert-buffer'). This
+cancels your last check-out, leaving the file unlocked. If you want to
+make a different set of changes, you must first check the file out
+again. `C-x v u' requires confirmation, unless it sees that you
+haven't made any changes since the last checked-in version.
+
+ `C-x v u' is also the command to use if you lock a file and then
+don't actually change it.
+
+ You can cancel a change after checking it in, with `C-x v c'
+(`vc-cancel-version'). This command discards all record of the most
+recent checked in version, so be careful about using it. It requires
+confirmation with `yes'. By default, `C-x v c' reverts your workfile
+and buffer to the previous version (the one that precedes the version
+that is deleted), but you can prevent the reversion by giving the
+command a prefix argument. Then the buffer does not change.
+
+ This command with a prefix argument is useful when you have checked
+in a change and then discover a trivial error in it; you can cancel the
+erroneous check-in, fix the error, and repeat the check-in.
+
+ Be careful when invoking `C-x v c', as it is easy to throw away a
+lot of work with it. To help you be careful, this command always
+requires confirmation with `yes'.
+
+ You can register the visited file for version control using
+`C-x v i' (`vc-register'). If the variable `vc-default-back-end' is
+non-`nil', it specifies which version control system to use; otherwise,
+this uses RCS if it is installed on your system and SCCS if not. After
+`C-x v i', the file is unlocked and read-only. Type `C-x C-q' if you
+wish to edit it.
+
+ By default, the initial version number is 1.1. If you want to use a
+different number, give `C-x v i' a prefix argument; then it reads the
+initial version number using the minibuffer.
+
+ If `vc-initial-comment' is non-`nil', `C-x v i' reads an initial
+comment (much like a log entry) to describe the purpose of this source
+file.
+
+ To specify the version number for a subsequent checkin, use the
+command `C-u C-x v v'. `C-x v v' (`vc-next-action') is the command
+that `C-x C-q' uses to do the "real work" when the visited file uses
+version control. When used for checkin, and given a prefix argument,
+it reads the version number with the minibuffer.