diff --git a/reference/http/functions/headers-sent.xml b/reference/http/functions/headers-sent.xml
index f70c73187b..97fab7f39c 100644
--- a/reference/http/functions/headers-sent.xml
+++ b/reference/http/functions/headers-sent.xml
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="iso-8859-1"?>
-<!-- $Revision: 1.2 $ -->
+<!-- $Revision: 1.3 $ -->
 <!-- splitted from ./en/functions/http.xml, last change in rev 1.7 -->
   <refentry id="function.headers-sent">
    <refnamediv>
@@ -14,10 +14,14 @@
      </methodsynopsis>
     <para>
      This function returns &true; if the HTTP headers have already been
-     sent, &false; otherwise.
+     sent, &false; otherwise. You can't add any more header lines using
+		 the <function>header</function> function once the header block has
+		 already been sent. Using this function you can at least prevent
+		 getting the "Duplicate headers ..." error messages.
     </para>
     <para>
-     See also <function>header</function>
+     See also <function>header</function> for a more detailed discussion
+		 of the matters involved.
     </para>
    </refsect1>
   </refentry>