diff --git a/reference/session/constants.xml b/reference/session/constants.xml
index 5826d4e017..8c3905b337 100644
--- a/reference/session/constants.xml
+++ b/reference/session/constants.xml
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="iso-8859-1"?>
-<!-- $Revision: 1.3 $ -->
+<!-- $Revision: 1.4 $ -->
 <section id="session.constants">
  &reftitle.constants;
  &extension.constants;
@@ -11,8 +11,9 @@
    </term>
    <listitem>
     <simpara>
-     Constant containing the session name and session ID in
-     the form of <literal>"name=ID"</literal>.
+     Constant containing either the session name and session ID in
+     the form of <literal>"name=ID"</literal> or empty string
+     if session ID was set in an appropriate session cookie.
     </simpara>
    </listitem>
   </varlistentry>