diff --git a/doc/lispref/ChangeLog b/doc/lispref/ChangeLog
index 123f1731311..c23073e4254 100644
--- a/doc/lispref/ChangeLog
+++ b/doc/lispref/ChangeLog
@@ -2,6 +2,7 @@
 
 	* variables.texi (File Local Variables):
 	Update hack-local-variables `mode-only' return value.
+	Add some more details on what this function does in the other case.
 
 2011-05-19  Glenn Morris  <rgm@gnu.org>
 
diff --git a/doc/lispref/variables.texi b/doc/lispref/variables.texi
index 7a8536933dc..08712466b5c 100644
--- a/doc/lispref/variables.texi
+++ b/doc/lispref/variables.texi
@@ -1670,7 +1670,10 @@ This function works by walking the alist stored in
 @code{file-local-variables-alist} and applying each local variable in
 turn.  It calls @code{before-hack-local-variables-hook} and
 @code{hack-local-variables-hook} before and after applying the
-variables, respectively.
+variables, respectively.  It only calls the before-hook if the alist
+is non-@code{nil}; it always calls the other hook.  This
+function ignores a @samp{mode} element if it specifies the same major
+mode as the buffer already has.
 
 If the optional argument @var{mode-only} is non-@code{nil}, then all
 this function does is return a symbol specifying the major mode,