updated for version 7.4.191
Problem:    Escaping a file name for shell commands can't be done without a
            function.
Solution:   Add the :S file name modifier.
diff --git a/runtime/doc/usr_40.txt b/runtime/doc/usr_40.txt
index b1108a5..9d70648 100644
--- a/runtime/doc/usr_40.txt
+++ b/runtime/doc/usr_40.txt
@@ -209,7 +209,7 @@
 separates the two commands.  This also means that a | character can't be used
 inside a map command.  To include one, use <Bar> (five characters).  Example:
 >
-	:map <F8> :write <Bar> !checkin %<CR>
+	:map <F8> :write <Bar> !checkin %:S<CR>
 
 The same problem applies to the ":unmap" command, with the addition that you
 have to watch out for trailing white space.  These two commands are different: