2 files changed, 11 insertions, 1 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 67de518e56d..fe43c7ad0aa 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,8 @@
+2013-11-05  Xue Fuqiao  <xfq.free@gmail.com>
+
+        * international/characters.el (glyphless-char-display-control):
+        Add usage note.
+
 2013-11-05  Bozhidar Batsov  <bozhidar@batsov.com>
 
         * progmodes/python.el (python-mode): Remove incorrect text from docstring.
diff --git a/lisp/international/characters.el b/lisp/international/characters.el
index ab83ff0034a..2195308737c 100644
--- a/lisp/international/characters.el
+++ b/lisp/international/characters.el
@@ -1485,7 +1485,12 @@ METHOD must be one of these symbols:
   `empty-box':  display an empty box.
   `acronym':    display an acronym of the character in a box.  The
                 acronym is taken from `char-acronym-table', which see.
-  `hex-code':   display the hexadecimal character code in a box."
+  `hex-code':   display the hexadecimal character code in a box.
+
+Do not set its value directly from Lisp; the value takes effect
+only via a custom `:set'
+function (`update-glyphless-char-display'), which updates
+`glyphless-char-display'."
   :version "24.1"
   :type '(alist :key-type (symbol :tag "Character Group")
                 :value-type (symbol :tag "Display Method"))