diff --git a/functions/fdf.xml b/functions/fdf.xml
index 89e5e28ac6..8491d70a8c 100644
--- a/functions/fdf.xml
+++ b/functions/fdf.xml
@@ -561,8 +561,9 @@ unlink("outtest.fdf");
      <function>fdf_set_encoding</function> sets the character
      encoding in FDF document <parameter>fdf_document</parameter>. 
      <parameter>encoding</parameter> should be the valid encoding 
-     name such as "<literal>Shift-JIS</literal>" or 
-     "<literal>Unicode</literal>".
+     name. The valid encoding name in Acrobat 5.0 are 
+     "<literal>Shift_JIS</literal>", "<literal>UHC</literal>",
+     "<literal>GBK</literal>","<literal>BigFive</literal>".
     </para>
     <para>
      The <function>fdf_set_encoding</function> is available in