diff --git a/doc/misc/tramp.texi b/doc/misc/tramp.texi
index 87164bfce31..331ec594bf0 100644
--- a/doc/misc/tramp.texi
+++ b/doc/misc/tramp.texi
@@ -672,8 +672,10 @@ as the @option{rsh} method.
 
 This method does not connect to a remote host at all, rather it uses
 the @command{su} program to allow you to edit files as another user.
-With other words, a specified host name in the file name is silently
-ignored.
+That means, the specified host name in the file name must be either
+@samp{localhost} or the host name as returned by the function
+@command{(system-name)}.  For an exception of this rule see
+@ref{Multi-hops}.
 
 
 @item @option{sudo}