diff --git a/features/commandline.xml b/features/commandline.xml
index 3932a1203d..cc342ffd5a 100644
--- a/features/commandline.xml
+++ b/features/commandline.xml
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="iso-8859-1"?>
-<!-- $Revision: 1.50 $ -->
+<!-- $Revision: 1.51 $ -->
 <chapter xml:id="features.commandline" xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink">
  <title>Using PHP from the command line</title>
  <para>
@@ -289,6 +289,12 @@ php -r 'fwrite(STDERR, "stderr\n");'
      You do not need to explicitly close these streams, as they are closed
      automatically by PHP when your script ends.
     </para>
+    <note>
+     <para>
+      These constants are not available in case of reading PHP script from
+      <literal>stdin</literal>.
+     </para>
+    </note>
    </listitem>
    <listitem>
     <para>