-WARNING: If the transfer is interrupted, you will have an inconsistent file
-and the transfer should be run again.
+WARNING: The file's data will be in an inconsistent state during the
+transfer (and possibly afterwards if the transfer gets interrupted), so you
+should not use this option to update files that are in use. Also note that
+rsync will not update a file inplace that is not writable by the receiving
+user.