Better explanation of --force. It is applicable whenever --delete is

not in effect.

rsync.yo

@@ -489,13 +489,10 @@ then use the --delete-after switch.
 dit(bf(--ignore-errors)) Tells --delete to go ahead and delete files
 even when there are IO errors.
 
-dit(bf(--force)) This option used to alter the behavior of the --delete
-option to force deletion of non-empty directories, but that happens now
-anyway because rsync does deletes in depth-first order.  The only known
-difference that --force makes now is an obscure case where the source is a
-non-directory (for example a file or a symlink) but the destination is a
-directory that contains a directory by the same name as the source while
---recursive mode is in effect.
+dit(bf(--force)) This options tells rsync to delete directories even if
+they are not empty when they are to be replaced by non-directories.  This
+is only relevant without --delete because deletions are now done depth-first.
+Requires the --recursive option (which is implied by -a) to have any effect.
 
 dit(bf(-B , --block-size=BLOCKSIZE)) This controls the block size used in
 the rsync algorithm. See the technical report for details.