diff --git a/reference/session/reference.xml b/reference/session/reference.xml
index 740d1c8f59..1620193923 100644
--- a/reference/session/reference.xml
+++ b/reference/session/reference.xml
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="iso-8859-1"?>
-<!-- $Revision: 1.10 $ -->
+<!-- $Revision: 1.11 $ -->
  <reference id="ref.session">
   <title>Session handling functions</title>
   <titleabbrev>Sessions</titleabbrev>
@@ -176,6 +176,14 @@
         of seconds after which data will be seen as 'garbage' and
         cleaned up.  
        </simpara>
+       <note>
+        <simpara>If you are using the default file-based session handler, your
+        filesystem must keep track of access times (atime).  Windows FAT does
+        not so you will have to come up with another way to handle garbage
+        collecting your session if you are stuck with a FAT filesystem or any
+        other fs where atime tracking.
+        </simpara>
+       </note>
       </listitem>
       <listitem>
        <simpara>