diff --git a/appendices/ini.xml b/appendices/ini.xml
index 165a07eb10..2033ed870a 100644
--- a/appendices/ini.xml
+++ b/appendices/ini.xml
@@ -3551,6 +3551,11 @@
    &php.ini; directives together and to get them to act upon a particular host
    or on a particular path.
   </para>
+  <para>
+   These sections are used only in CGI/FastCGI mode and they can not set
+   <link linkend="ini.extension">extension</link> and <link
+   linkend="ini.zend-extension">zend_extension</link> directives.
+  </para>
   <para>
    <table>
     <title>Sections</title>