to become a backup when the next save is done,
and unconditionally makes the previous version into a backup file.
-With argument of 0, never makes the previous version into a backup file.
+With argument of 0, never make the previous version into a backup file.
If a file's name is FOO, the names of its numbered backup versions are
FOO.~i~ for various integers i. A non-numbered backup file is called FOO~.
If `delete-old-versions' is nil, system will query user
before trimming versions. Otherwise it does it silently.
+If `vc-make-backup-files' is nil, which is the default,
+ no backup files are made for files managed by version control.
+ (This is because the version control system itself records previous versions.)
+
See the subroutine `basic-save-buffer' for more information."
(interactive "p")
(let ((modp (buffer-modified-p))