diff --git a/reference/mcal/reference.xml b/reference/mcal/reference.xml
index 4ec5d18957..7d83cb1f99 100644
--- a/reference/mcal/reference.xml
+++ b/reference/mcal/reference.xml
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="iso-8859-1"?>
-<!-- $Revision: 1.4 $ -->
+<!-- $Revision: 1.5 $ -->
  <reference id="ref.mcal">
   <title>MCAL functions</title>
   <titleabbrev>MCAL</titleabbrev>
@@ -38,6 +38,14 @@
      for setting, initializing, and retrieving the event structure
      values.
     </para>
+    <note>
+     <para>
+      PHP had an ICAP extension previously, but the original library
+      and the PHP extension is not supported anymore. The suggested
+      replacement is MCAL.
+     </para>
+    </note>
+    
    </section>
    
    <section id="mcal.requirements">